Move duplicate checking till after routing. Should fix several subtle

[users/heiko/exim.git] / doc / doc-misc / WishList

$Cambridge: exim/doc/doc-misc/WishList,v 1.28 2005/04/04 08:27:28 ph10 Exp $

EXIM 4 WISH LIST
----------------

Even when it was first released, Exim 4 had a Wish List because not all the
things suggested for it were implemented. The list has not stopped growing...

Another reason it is so long is that I have retained some items from the Exim 3
Wish List that never got implemented, but which seem reasonable possibilities
for later addition to Exim 4.

I have guessed at the amount of work involved, and categorized the items as
Tiny, Small, Medium, Large, or Unknown. The guesses are not based on any
detailed investigation, so must be taken as very rough.


------------------------------------------------------------------------------
------------------------------------------------------------------------------
-----                Retained from the Exim 3 Wish List                 ------
------------------------------------------------------------------------------
------------------------------------------------------------------------------

(10) 13-Jul-98  M  more flexibility for pipe returns
Ben Smithurst

The ability to specify more precisely what happens concerning the return code
from the pipe and the presence/absence of STDOUT/STDERR is requested. The
particular configuration that was requested was:

> if the command exited EX_OK, *and* produced nothing on STDOUT or
> STDERR, it succeeded...
> if the command exited EX_TEMPFAIL, defer, regardless of
> STDOUT/STDERR...
> otherwise freeze the message (this will get my attention by way of
> freeze_tell_mailmaster)...
------------------------------------------------------------------------------

(11) 17-Jul-98  G  support for DSN
Andy Mell

It is unclear to me how this should work in the presence of aliases and
forwarding. Local deliveries would have to explicitly configured as deliveries
or relaying or whatever. A substantial amount of code is probably needed.

Jeffrey Goldberg
I have nothing to add except to say that for many of the reasons you've
stated, I don't think that DSN is coherent enough to be worth the effort
to implement.

Another comment:

  I thought the RFC was pretty clear on this. In a nutshell, if the
  delivery rewrites the envelope from address, it's considered a
  terminal delivery (i.e. delivery to a mailing list exploder), otherwise
  treat it as a forwarding operation (the /etc/aliases case). I would
  treat a .forward expansion as a final delivery event (it got to the
  user as far as the MTA is concerned).

  Yes, we need the DSN syntax. We also require the complete semantics of
  NOTIFY=SUCCESS,FAILURE for our application to work.

  Electronic Bill Presentment is really going to push the need for
  DSN support in MTAs. We just don't want to get stuck in a situation
  where we're faced with a non-DSN-aware MTA when we go to install
  our bill/statement engine, thus our interest in what the MTA vendors
  are planning to do about DSN.
------------------------------------------------------------------------------

(41) 14-Oct-98  M  Find a way of modifying header lines
Oliver Smith

The problem with header_remove followed by header_add is that you can't refer
to the previous value of the header when adding a replacement. This could be
solved with a replace_header option.
------------------------------------------------------------------------------

(43) 15-Oct-98  M  Sender rewrite *after* SMTP incoming checks
Andreas Edler

The anti-relaying check happens after the sender has been rewritten; there are
times when it would be helpful to do the check on the original sender, not on
the rewritten one. Quite how to configure this I'm not sure.

A related suggestion (from Steve Sargent) is to retain the original sender
address and make it accessible somehow.
------------------------------------------------------------------------------

(46) 20-Oct-98  L  SMTP protocol hooks
Malcolm Ray

"But there are enough broken SMTP implementations to make me wonder whether
there isn't a case for providing hooks for tweaking the SMTP transport's
protocol exchange. Something which would allow me to say things like 'if, when
talking to lame.example.com, you get a 251 response to a MAIL command, rewrite
the response to 501 before continuing'."
------------------------------------------------------------------------------

(50) 13-Nov-98  M  A "Focus" option for eximon
Frank Elsner

This is the opposite of "Hide"; it just displays a certain subset. Hmm. Could
something clever be done with regular expressions?
------------------------------------------------------------------------------

(61) 22-Dec-98  M  Send failed error messages to somebody
Harald Meland

With sendmail, the failed error message is made into a error message,
with both envelope sender and recipient set to MAILER-DAEMON.  The
original, bogus-envelope-sender message is then available to whoever
receives MAILER-DAEMON's mail. A more flexible approach would be to
specify a specific recipient.
------------------------------------------------------------------------------

(81) 01-Mar-99  M  Addition of Content-MD5 support
Martin Hamilton

Martin supplied a suggested patch at
http://www.net.lut.ac.uk/~martin/antispam/exim-hacks/
------------------------------------------------------------------------------

(85) 15-Mar-99  M  ability to rewrite addresses in non-standard headers
Dave Lewney
John Holman

Such as "return-receipt-to". See also 41.
------------------------------------------------------------------------------

(90) 21-Apr-99  M  change wild prefix/suffix greediness
Ben Smithurst

Currently, when prefix or suffix containing * is set on a director, and the
fixed part occurs more than once in a local part, the length of the prefix or
suffix is maximized. For example, with suffix = -* and a local part of
foo-bar-baz the suffix is taken as bar-baz, leaving the local part as foo.
An option is proposed to invert this rule.
------------------------------------------------------------------------------

(91) 26-Apr-99  S  make queue_run_in_order to newest first
"Andreas M. Kirchwitz"

The tidiest thing would be to have queue_run_order={random,oldest,newest},
and make queue_run_in_order obsolete.
------------------------------------------------------------------------------

(93) 04-May-1999  L  fallback_transport

This would be a generic transport option, specifying a different transport to
be used if the first one failed. Failed hard, or failed soft? Or an option?
And if failed hard, is a bounce message sent as well, or not? There are uid
issues. Remote delivery would have to be done always in a subprocess so that
the main process could retain privilege in case the fallback transport was
local. That could be conditional. That's why this is labelled "Large". Some of
the things people want to do with this can be done by variations in the
routers, e.g. use $message_age to switch routers.
------------------------------------------------------------------------------

(94) 13-May-1999  M  message to go with -Mg
Dave Holland
Alan Thew

So the admin can pass back a reason.
------------------------------------------------------------------------------

(99) 28-May-1999  M  header to list failures for syntax_errors_to
mark david mcCreary

"I use the syntax_errors_to feature to email a copy of the error message.
It would be helpful to have the X-Failed-Receipients header in there,
identifying which addreses(s) are the problem, so that I don't have to
parse the body of the email message to figure out which addresses."
------------------------------------------------------------------------------

(100) 04-Jun-1999  S  admin_users option, like trusted_users
Paul Mansfield
------------------------------------------------------------------------------

(102) 21-Jun-1999  M  expanded basic variables
Julian King

Oh, and a wishlist entry, qualify_domain, and preferably other variables
can be set with a $lookup in the first part of the exim configuration
file, perhaps by an equivalent to backticks in shell script ("`command`")?
------------------------------------------------------------------------------

(105) 28-Jun-1999  M  MIME-format bounce messages
Paul Makepeace

"Is there any work going/gone on/planned to enable exim to report delivery
status notifications using RFC1892 multipart/report MIME messages? It would be
great to have errors reported in a message/rfc822 attachment."

Jeffrey Goldberg
"I like plain bounces, so would hope that if you do this, that it be
configurable. I think that even for those who want it, it shouldn't be very
high on the wish list priority."

Other suggestions: toggle for bounces/warnings; override max_return for
certain addresses; use plain text if original not MIME. See Paul's hack
for background of what to do.

Nigel suggests using a specially named autoreply transport to generate bounces;
people could then replace this with another transport (e.g. pipe) if they want
to customize it themselves.

Eli Chen posted an unconditional patch for 3.32 that does some of this work.
That could form a basis.
------------------------------------------------------------------------------

(107) 12-Jul-1999  S  defer transport at given load level
Marc Haber

------------------------------------------------------------------------------

(108) 16-Jul-1999  S  remote sort by numbers of recipients
mark david mcCreary

In the absence of remote_sort, sort remote domains by the number of recipients
in each.
------------------------------------------------------------------------------

(114) 11-Nov-1999 S  List of possible outgoing interfaces

Allow the smtp "interface" option to be a list: try them in turn until one
is found to work. Also allow masks to specify a range of addresses.
------------------------------------------------------------------------------

(123) 23-Dec-1999 L  Use AUTH + TURN for dial-in hosts
Andrew Tverdokhleb

The way to do this would be to have Exim deliver messages into per-host
directories in, say, BSMTP format. Accept TURN if authenticated, and cause it
to run a helper program that is passed the socket in order to deliver the mail.
Provide a helper program!
------------------------------------------------------------------------------

(125) 04-Jan-2000 L  Use shared memory segment for queue list
Theo Schlossnagle

The idea is that a queue-runner that finds no existing shared segment should
create one (if configured - possibly some fixed size) and all Exim processes
should maintain a list of messages in it, thereby saving on directory scans
when there are lots of messages. This needs a lot of careful thought to try to
eliminate any possibility of data loss. The interlocking could be quite tricky.
Further posters suggested using a db file to hold the list. See also 127.
------------------------------------------------------------------------------

(129) 14-Jan-2000 L  Dynamically loadable lookup modules
Steve Haslam

Suggested patch provided.
------------------------------------------------------------------------------

(131) 17-Jan-2000 T  Facility for assuming existence for EACCES
Peter Radcliffe

The opposite option for "+" in require_files: assume existence if cannot
peer into the directory (+ assumes non-existence).
------------------------------------------------------------------------------

(131) 29-Feb-2000 M? Control total number of outgoing SMTP calls
Brian White

This is for hosts with slow connections. Could some modification of
serialize_hosts be used for this? Or maybe use a semaphore? They seem to
be quite widely available.
------------------------------------------------------------------------------

(132) 01-Mar-2000 S  Lookup host name from outgoing interface
Vadim Vygonets

Instead of primary_hostname, look up the name for the interface that is being
used for sending. Suggested patch supplied, but this should be an option of the
smtp transport.
------------------------------------------------------------------------------

(133) 06-Mar-2000 S  Filter option not to log "previously sent"
Bruce Bowler

This is when using the "log" option of the autoreply driver.
------------------------------------------------------------------------------

(134) 09-Mar-2000 S  Option to remove attachments when bouncing
------------------------------------------------------------------------------

(136) 13-Mar-2000 S/M Option for aliasfile to suppress "me too"

Could be tricky determining who "me" is.
------------------------------------------------------------------------------

(143) 08-May-2000 S  Make quota_warn_threshold into a list
David Carter

So several warnings could be generated as the mailbox got bigger and bigger.
------------------------------------------------------------------------------

(146) 15-May-2000 M  Allow SMTP error codes in retry rules

This would allow special handling of certain errors from certain hosts. In
particular, it would allow failing of certain 4xx codes.

This is now available for 4xx responses to RCPT commands. Is anything more
needed? Apparently, yes; there's been a request for a similar feature for MAIL
commands.
------------------------------------------------------------------------------

(148) 15-May-2000 S  Warn recipient if message rejected for quota excession.
Heinz Ekker

Maybe not all that small, because the possibility of retrying must be taken
into account.
------------------------------------------------------------------------------

(149) 19-May-2000 L  Make added headers visible in filters and other places
Hans Morten Kind

Headers added by directors/routers are not visible in subsequent processing.
This is a request to make them visible. What about removed headers? This could
be tricky to specify, hence the L.

A separate but related issue is the effect of headers added by "unseen"
directors. These are documented in chapter 19 as not being accumulated. Should
any change be made?
------------------------------------------------------------------------------

(155) 16-Jun-2000 M  Special handling for certain hosts
mark david mcCreary

A means of changing the transport depending on the host name/IP of the most
preferred MX record so that all domains that route to certain hosts can be
handled specially. Maybe this could be a variable that is available in the
expansion of the "transport" option.
------------------------------------------------------------------------------

(158) 29-Jun-2000 S  Configure "From" in bounces
Ben Parker

Cf Reply-To.
------------------------------------------------------------------------------

(159) 07-Jul-2000 M  Keep messages for fixed time
Gary Palmer

An option to keep messages on the queue for a specified time, even if all their
destination hosts have timed out.
------------------------------------------------------------------------------

(164) 17-Aug-2000 S  sender_unqualified_auth_hosts

To allow authenticated hosts to send unqualified addresses. Presumably it
needs received_... as well.
------------------------------------------------------------------------------

(167) 05-Sep-2000 L  Support for ODBC

This would allow access to databases that don't have native support built into
Exim. See http://www.openlinksw.com/info/docs/rel3doc/unix/odbcsdk.htm
------------------------------------------------------------------------------

(168) 06-Sep-2000 M  Deliver messages that alias to nothing to a given address
Dr ZP Han

If other people are managing alias lists, and one is empty, bounce that
delivery to a given address rather than freezing the message. Use the errors_to
address?
------------------------------------------------------------------------------

(172)  11-Sep-2000 S  Allow file/directory in appendfile to override
"Michael J. Tubby"

When appendfile is called from forward or filter files, it ignores file or
directory settings. Maybe they should override. The path set by the forward or
filter is available in $address_file these days, so it could be used to create
a longer path.
------------------------------------------------------------------------------

(173)  18-Sep-2000 S  A way of doing lsearches with EOL terminated keys
Jason Robertson

This is for looking up things like subject contents. Probably need an option to
exim_dbmbuild to make them into DBM files.
------------------------------------------------------------------------------

(174)  19-Sep-2000 S  A way of using a different port for fallback hosts.
Dean Brooks
------------------------------------------------------------------------------

(181)  10-Nov-2000 S  Compile-time options for ignoring Sendmail options

So that new ones could be accommodated easily.
------------------------------------------------------------------------------

(183)  04-Dec-2000 L  dns_means_nonexist_after
Dave C.

In other words, wait a bit before giving up. This needs a mechanism for
remembering, which is not currently available. To be borne in mind for the
future.
------------------------------------------------------------------------------

(184)  04-Dec-2000 M  Log more details of local caller
J. Nick Koston

"I was wondering if it was possible for exim to log the parent pid's cwd and
exe when it is called from a script/invoked by actually running /usr/sbin/exim
or /usr/sbin/sendmail."  Question: is this information actually/easily
available to Exim? Needs investigation.
------------------------------------------------------------------------------

(186)  19-Dec-2000 S  A simple utility to reset a retry time
Marc Haber

Basically, to do what exim_fixdb "delete" can do, but straightforwardly. There
could be an interface from eximon.
------------------------------------------------------------------------------

(187)  02-Jan-2001 M  Wildcarding in headers_remove
Tamas TEVESZ

What I'd like to see is it to handle globs (or regexps, but i'm not sure this
latter would worth the hassle), in a way like:

        headers_remove = "X-*:Additional-header"
------------------------------------------------------------------------------

(188)  02-Jan-2001 S  Make pipe timeout a temporary error
Georg v.Zezschwitz

A way to make a timeout into a temporary error.
------------------------------------------------------------------------------

(190)  03-Jan-2001 M  Multiple message operations in eximon
------------------------------------------------------------------------------

(195)  19-Mar-2001 T TCP window size

TCP window size for receiving/sending, SMTP client/server.
------------------------------------------------------------------------------
------------------------------------------------------------------------------



------------------------------------------------------------------------------
------------------------------------------------------------------------------
-----            Things that didn't make it into Exim 4                 ------
------------------------------------------------------------------------------
------------------------------------------------------------------------------

. An option to send messages to postmaster when ignore_errmsg_errors_after
times out.

. When an address is being routed, its constituents are in $local_part and
$domain, but there is currently no variable that contains the whole thing. It
could be put into $recipient, but that risks confusion with $recipients
(which is available in system filters). Maybe $address could be used?

. The ability to relay to host X without knowing all the domains that host X
might have. At ACL time, one would need to verify the recipient, and determine
that it routed to host X.

. A new lookup library that operates on a specially prepared file of IP
addresses and masks so that a single "lookup" yields a yes/no answer. This
should be a freestanding thing - needs a utility to build the file from a list.

. People want to change the wording of messages; can we find an efficient way
of allowing this? (Maybe put all messages into a separate module?) The problem
is not in the messages themselves, but in the values that get inserted into
messages. Would have to invent a new kind of function that used identified
values rather than positional ones. Use GNU gettext?

. Invent lf_hosts for those that may use LF without CR. Any other RFC
things we need to worry about?

. A user would really like to see something similar, perhaps with
"ID=$authenticated_id", similar to "helo=" and "ident=" in the default received
header. BUT there are security issues. Maybe give it as a commented out option
in the default configuration?

. Consider expanding further options that take integer values. What about
smtp_xxx options for different limits at different times of day (for example)?
What about tls_advertise_hosts (so can look at incoming IP/port)?

. How about a "hold hosts" option (cf hold_domains) to hold delivery to certain
hosts?

. Allow user filters to use "headers add", but probably not remove. Or maybe
just implement "allow" options for both of these features.

. Have the return from pipe in a variable, so that (e.g. error_message_file)
can make use of it.

. Implement randomize for ldap/sql servers.

. Add an option for ETRN that says "wait for the command to finish, and use its
stdout as the SMTP response."

. -odsomething for "ignore retry when doing immediate delivery".

. Add an option to the smtp transport to make it treat 5xx on connection as if
it were 4xx. Or possible add a sophisticated "after command X, treat xxx as
yyy".

. A way of rewriting addresses in non-standard header lines such as
Mail-Followup-To.

. Global option to enable initgroups() for exim uid. Default off.

. When verifying a sender, should it be rewritten with any T rewrites, because
it would be so rewritten if it actually was a recipient in a message?

. Sean Witham wants a way of defining macros that are not privileged, and a
sort of #ifdef structure that allows for different configurations in the same
file.

. Allow :fail: to specify that 551 be used instead of 550. Maybe allow a code
at the start, optionally? What about :defer:?

. SMTP timeout in middle of receiving message: log sender address if known, and
possibly message_id if known.

. Make -brw show rewrites for transports too.

. Have the MTA log destinations that have timed-out on a ident request and
no longer send rfc1413_queries to them. Add an option for how not to cache
these entries.

. Options and/or a utility to enable non-privileged users to view the queue
(e.g. -bpp), manipulate their own messages, etc.

. Specify a port along with a host in a route_list.

. A generalized "From" escaping scheme that also escapes >From so that the
whole thing can be reversed.

. There was a request for the \dns_again_means_nonexist\ option not to be
instantaneous, but to operate only after the DNS has been giving "try again"
for some time. Use the misc hints database.



------------------------------------------------------------------------------
------------------------------------------------------------------------------
-----                     The Exim 4 Wish List                          ------
------------------------------------------------------------------------------
------------------------------------------------------------------------------

(1)  01-Jan-02  U  Use of dynamically loaded libraries.

People want Exim to use dynamically loaded modules for a variety of reasons.
When I started to create Exim, I never expected anything other than source
distribution; the RPMs and inclusions in OS distributions caught me by
surprise. I know very little about the mechanics of dynamic loading, but I'm
aware that not all operating systems support it. I'm also aware that not all
people support it!

Furthermore, a way round this might be to supply more hooks along the lines of
local_scan(). Then people can write their own dynamic loaders if they want.
------------------------------------------------------------------------------

(3)  01-Jan-02  U  Test for over-quota at SMTP time

This is a hard one, because the only way to test for over quota is to try to
deliver a message, certainly if system quotas are being used. And also, the
only available size at RCPT time is the SIZE option, though of course the test
could be run at DATA time. I think maybe we leave this one to an external
program, and require people to use ${run} to access the data. Let someone else
figure out how to extract the current mailbox size!

One suggestion is to implement

  ${file_size:/path/to/file}
  ${directory_size:/path/to/directory}

so that explicit checks can be done. It may be necessary to have four
operators, two being based on the block count, and two showing the "visible"
size. Directory scanning is expensive; is there any scope for caching? It would
seem not (you don't often get two addresses to the same user).
------------------------------------------------------------------------------

(6)  01-Jan-02  S  Option to disable the use of -t
Dave C.

Would require work so that Exim itself doesn't use -t.
------------------------------------------------------------------------------

(7)  01-Jan-02  M  Avoid showing LDAP passwords in log lines for LDAP errors
John W Baxter

May be tricky, because at the higher levels, the format of the query is not
understood.
------------------------------------------------------------------------------

(8)  01-Jan-02  S  Expand once_repeat in autoreply
John Jetmore
------------------------------------------------------------------------------

(9)  01-Jan-02  S  Headers as well as body in file for autoreply
Florian Laws
------------------------------------------------------------------------------

(10) 01-Jan-02  T  Make "true" and "false" valid expansion conditions

This might help with "and" and "or" when one of the sub-conditions is, for
example, a lookup.
------------------------------------------------------------------------------

(11) 01-Jan-02  S  Allow a filter to include another file.
------------------------------------------------------------------------------

(12) 01-Jan-02  M  Support for different SQL servers per query

In other words, the global mysql_servers etc. is too restrictive.
------------------------------------------------------------------------------

(14) 01-Jan-02  M? Support for Sendmail milters

This could perhaps be done by extending the local_scan() idea and providing a
"standard" module which interfaced to milter.
------------------------------------------------------------------------------

(15) 01-Jan-02  M  More hooks like local_scan()

One request has been for a similar hook at logging time. For other SMTP
interactions, maybe a hook into the ACL? See also 79 and 218 and 301.
------------------------------------------------------------------------------

(17) 11-Jan-02  M  The construction of config.h needs refactoring

This has been hacked about substantially since the original implementation.
Given that there is a program (buildconfig), the messing around with the
environment could be abolished. Also, the distinction between "yes" and "no"
isn't always properly made (tests for #ifdef don't care about the value).
------------------------------------------------------------------------------

(18) 24-Jan-02  S  Make $value retain its value after a top-level expansion

This was specifically for use in filter files. Currently it reverts to empty
as a consequence of save/restore for every lookup. It might be confusing to
do otherwise, however.
------------------------------------------------------------------------------

(19) 29-Jan-02  L  Use of multiple DBM libraries

The problem is how to handle conflicting function names. Much research is
needed.
------------------------------------------------------------------------------

(20) 29-Jan-02  S  Make system filter refreeze after manual thaw

Currently, a "freeze" in a system filter doesn't freeze after a manual thaw.
------------------------------------------------------------------------------

(21) 12-Feb-02  S  Expand return_size_limit
Joachim Wieland

Is this really worth it? A per-transport value is also suggested - that would
mean remembering the value with each failed address and taking a minimum or
a maximimum (which?).
------------------------------------------------------------------------------

(24)  21-Feb-02 ?  A way of testing TLS using -bh
------------------------------------------------------------------------------

(27)  06-Mar-02 M  Distinguishing between different temporary callout errors

The request was to distinguish between a 4xx error and a failure to connect.
Problem is: how to cope when there is more than one host? Maybe only if ALL
fail to connect. An option like /callout_no_connect_ok.
------------------------------------------------------------------------------

(30)  12-Mar-02 S  Add "recipients" precondition to routers.

This would avoid having to use "condition". (See also requirement for $address
mentioned above.) However, it would also require adding a caching feature, and
probably $recipient_data (cf $domain_data).
------------------------------------------------------------------------------

(31)  21-Mar-02 S  Variables that indicate 8-bit message and 8-bit host, and
                   a way of using them to suppress a transport filter

A variable that is set if the message contains 8-bit characters, and another
that is set during the smtp transport if the host supports 8-bit. Then we also
need a condition that's expanded in the transport to control whether the filter
is run or not (e.g. transport_filter_condition).
------------------------------------------------------------------------------

(32)  22-Mar-02 M  More info about callout fails for header sender verify

When there's a callout failure for an envelope address, the error message
contains details (by default) of the callout commands. This doesn't happen
for addresses in the header because there may be more than one of them, and
deciding how to give that information is tricky. Can we do better?
------------------------------------------------------------------------------

(33)  25-Mar-02 S  Option to assume nomatch in dnslist lookups that time out

Currently this causes a DEFER.
------------------------------------------------------------------------------

(34)  26-Mar-02 S  Access to DNS lookup functions via local_scan() API

This would make local_scan() writers lives easier for DNS usage.
------------------------------------------------------------------------------

(36)  02-Apr-02 ?  A way of throttling, but allowing, relaying that would
                   otherwise be denied

This was suggested in connection with anonymizing messages. The "wait" command
in ACLs goes some way towards this. Is it enough?
------------------------------------------------------------------------------

(41)  17-Apr-02 T  Make config.samples available as a directory for ftp

This is so that people can browse individual samples directly.
------------------------------------------------------------------------------

(42)  23-Apr-02 T  An option not to flatten newlines in $message_body.

Or maybe better to provide $message_body_nl so as to have both.
------------------------------------------------------------------------------

(43)  23-Apr-02 T  An option to treat 4xx as 5xx from STARTTLS

This would make Exim retry in clear unless the host is in hosts_require_tls.
------------------------------------------------------------------------------

(44)  24-Apr-02 ?  Use errors_to for timeouts after redirect syntax errors

A syntax error in redirection data (with skip_syntax_errors false) causes a
defer. Eventually, the address may time out. This suggestion is that, when it
does, the bounce is sent to errors_to rather than to the sender.
------------------------------------------------------------------------------

(45)  13-May-02 T  smtp_etrn_serialize_id = ....

The default behaviour would be equivalent to

  smtp_etrn_serialize_id = $smtp_command_argument
------------------------------------------------------------------------------

(47)  16-May-02 S  Access to all addresses in batched local delivery
Miquel van Smoorenburg

In a batched local delivery with more than one recipient, there's no way to
access the list of recipients for doing custom things, such as stuffing them
all into a header. (BSMTP is the only approach; not everybody can use it.)
Suggested patch supplied.
------------------------------------------------------------------------------

(48)  21-May-02 M  Support for ATRN (server and client)
Brian Candler

Server: If Exim had the ability to accept an ATRN command and then simply
invoke an external program, passing the SMTP stream on stdin and stdout and
the authenticated id as a parameter, that would do the job nicely.

Client: We need a variant of 'exim -bs' which would connect to a specified
host, send AUTH/ATRN, and then accept incoming messages as usual.
------------------------------------------------------------------------------

(50)  22-May-02 S?  Add comment (duplicate address) to Envelope-To:

This is just to minimize the confusion some people have. However, it is not
trivially easy to decide which to label as duplicates because of complications
with redirection. I'm not convinced it will actually reduce confusion.
------------------------------------------------------------------------------

(51)  07-Jun-02 S  Option to use another address in callout MAIL FROM

This would be an address to try if MAIL FROM:<> failed. Is this actually going
to be helpful? See also 101.
------------------------------------------------------------------------------

(53)  11-Jun-02 S  Make local_scan() dynamically loadable

David Woodhouse sent a patch. There's a more sophisticated one from Marc
Merlin. (See also Peter Benie's comments.) But should the base Exim have all
this in it?
------------------------------------------------------------------------------

(54)  11-Jun-02 S  Ignore -Ac if called as mailq

I am not sure if this makes sense. This flag requests a listing of a different
mail queue, but Exim doesn't work like that. Is is not better for people to be
aware of this?
------------------------------------------------------------------------------

(55)  13-Jun-02 M  Rewriting whole header lines
Dave C.

Current rewriting rules apply to individual addresses in header lines. This
feature would use a regex to match whole lines and replace them. It could be
useful for patching up syntactically invalid lines from crappy clients, before
the syntax check kicks in. (It might also be useful for hiding local host names
in Received: headers.)
------------------------------------------------------------------------------

(58)  26-Jun-02 ?  Extend PAM support

Apparently PAM can do challenge-response authentication. The Exim interface
can't handle this. Investigate and think about how to do this.
------------------------------------------------------------------------------

(59)  26-Jun-02 M  A "custom" authenticator

... that is simply a front end to external code. For example, there may be
an external API that hides the user password and does CRAM-MD5 when passed the
details of the challenge and response.
------------------------------------------------------------------------------

(60)  27-Jun-02 S  Make trusted_users a local part list

So that it can use lsearch etc.
------------------------------------------------------------------------------

(62)  28-Jun-02 S  Remove headers before DATA ACL
Patrice Fournier

"I'd like to be able to give Exim a list of headers that must be removed
from the message at arrival, before data_acl processing (and before the
rcpt_acl warn headers are added to the message)."
------------------------------------------------------------------------------

(63)  28-Jun-02 S  Access to ACL-added headers in ACLs
Patrice Fournier

"I'd like also to be able to look at the already added headers by a
rcpt_acl when still checking rcpt_acl (either later in the acl for the same
RCPT TO or for another RCPT TO)."
------------------------------------------------------------------------------

(65)  28-Jun-02 M  Expand fallback hosts

See also 174 of the Exim 3 list.
------------------------------------------------------------------------------

(66)  01-Jul-02 M  Use Berkeley DB 4 concurrent access features

This might give better performance on very busy sites by reducing the
contention for access to hints databases. Rob Butler points out that this could
also be useful to allow updates of other DB files used by Exim to happen
concurrently. Another thing to think about with BDB is the possible use of
B-trees.
------------------------------------------------------------------------------

(68)  01-Jul-02 S  Add sender host to delivery line

"Would it be possible to have a "sending_host_on_delivery" option that
logs the IP of the sending host in the => line?" Also requested was amount of
data transmitted for a non-delivery attempt.
------------------------------------------------------------------------------

(69)  03-Jul-02 T  Log selector to log whoson checs
Matt Bernstein

"I'd quite like a log_selector option which could spot you'd done a whoson
lookup in your DATA ACL and maybe log it as W=user."
------------------------------------------------------------------------------

(70)  09-Jul-02 S  A way of changing the RCPT address in an accept router

So as to avoid duplication problems when sending multiple addresses in multiple
copies to the same address.
------------------------------------------------------------------------------

(73)  17-Jul-02 M  Match a list from within a condition

e.g.  ${if matchdomain {$domain}{+domainlist} ...
      ${if matchhost {$sender_host_address}{1.2.3.4/10:2.3.4.5/16}...

Thought needed about how to handle host names. This may be too messy to specify
cleanly.

22-Apr-04: Implemented for domains, addresses, and local parts. Hosts are
too messy!

The only sensible approach seems to be to allow IP address arguments only.
Anything else should be diagnosed as an error. However, if a name appears in
the list, a PTR lookup should be done. This may require a lot of refactoring
in the code, because of the current assumption that were are (almost) always
dealing with THE sending host.
------------------------------------------------------------------------------

(74)  22-Jul-02 M  Extend -bV to do more semantic checking

For example, diagnose "local_hosts" that should probably be "+local_hosts".
------------------------------------------------------------------------------

(75)  23-Jul-02 S  Reference option on command line

The idea here is that a spam scanner that re-injects a message can supply a
reference on the command line that gets logged with R=.
------------------------------------------------------------------------------

(78)  30-Jul-02 S  Expand queue_only (and/or queue_only_file)

The requirement is to make it possible to queue messages if certain conditions
are met (e.g. messages from certain local users). See also 93.

This control can now be achieved in the ACL - is this still needed?
------------------------------------------------------------------------------

(79)  31-Jul-02 S  Additional info for log lines

An option to set an expanded string to be added to <= lines. And also for the
other delivery lines? See also 15.
------------------------------------------------------------------------------

(84)  09-Aug-02 S  Make interfaces available in a variable

Something like $local_interfaces. Maybe limit the max length.
------------------------------------------------------------------------------

(85)  12-Aug-02 S/M  Notice database connection failures

The small version of this just removes a server from the list within a single
Exim process when a connection to it fails. The bigger project would use the
retry database - but that has implications for bottlenecking and may not be
helpful. See also item 109. Another suggestion is to randomize the order in
which database servers are tried (randomize_database_servers). And another is
to measure response times and remember which server is fastest.
------------------------------------------------------------------------------

(87)  12-Aug-02 M  Partial lookups for query-style lookups

The suggestion is to allow the lookup to contain a keystring (same syntax as
single-key lookups) which is then permuted and place in a suitable variable
each time - $permuted_key or something.
------------------------------------------------------------------------------

(88)  20-Aug-02 S  Allow special retrying for forced defer

See also 146 in Exim 3 wish list above.
------------------------------------------------------------------------------

(89)  20-Aug-02 S  Also allow retry rules on routers and transports
------------------------------------------------------------------------------

(90)  23-Aug-02 M  Macros with arguments, a la C

I don't like this, because of the cost of frequent interpretation.
------------------------------------------------------------------------------

(93)  27-Aug-02 S  queue_only_condition
Peter A. Savitch

queue_only_condition global option, expanded string. This contain
condition, which if evaluated to `no' or `false' or `0', behaves like
queue_only (queue_only_load ?). Don't know what to do is the string
expansion fails with DEFER (either force queueing or continue with
immediate delivery). Another option can control Exim behaviour if the
expansion fails. Don't know how the name for it ;-) See also 78.

This control can now be achieved in the ACL - is the new feature now needed?
------------------------------------------------------------------------------

(95)  27-Aug-02 S  Log all parents as a router option

So that specific addresses can be logged like this. Should there be more log
selector options per router? Per transport?
------------------------------------------------------------------------------

(99)  28-Aug-02 L  Test pre-conditions in order given

This would get round certain problems with require_files. However, it is
totally incompatible, and therefore an "Exim 5" wish.
------------------------------------------------------------------------------

(101) 02-Oct-02 M  Callout and <> rejections

Some people don't want to fail the callout if the MAIL FROM:<> command is
rejected. Think of a way of handling this tidily. See also 51.
------------------------------------------------------------------------------

(102) 03-Oct-02 M  Log option to suppress message-id logging

M because it would involve a change to eximstats.
------------------------------------------------------------------------------

(106) 09-Oct-02 S  Appendfile to create directory not as user

Arrange for the setup entry to appendfile to create the directory under some
other uid (and with given owners/permissions?)
------------------------------------------------------------------------------

(109) 15-Oct-02 M  Remember when LDAP (etc) servers are down

The idea would be to use some kind of retry rule, just like for hosts.
See also 85.
------------------------------------------------------------------------------

(110) 18-Oct-02 M  errors_to for pipe command in filter

To work in the same was as errors_to for deliver commands.
------------------------------------------------------------------------------

(113) 15-Nov-02 M  support for XMLRPC

Patch supplied for 4.10 by Joel Vandal.
------------------------------------------------------------------------------

(114) 04-Dec-02 M  local_scan: return message on accept

(This actually dates from earlier.) The problem with this is that the string
currently passes into $local_scan_data. Thus, an incompatible change of some
sort would be required. Possibly a global that local_scan can set?
------------------------------------------------------------------------------

(118) 10-Dec-02 S  access to Perl from local_scan
------------------------------------------------------------------------------

(119) 12-Dec-02 M  ability to specify additional headers in an autoreply

This is so that vacation messages etc can have MIME headers that specify, for
example, the character set.
------------------------------------------------------------------------------

(125) 02-Jan-03 M  Per-host daemon logging

"So what I would like is an option like debug_hosts, that allows to specify
an hostlist, and if the current incoming/outgoing hosts matches, creates a
logfile like $hostname_(in|out).log in my logdirectory."
------------------------------------------------------------------------------

(127) 06-Jan-03 M  Different messages for different callout failures

The real requirement here is to detect when a callout "MAIL FROM:<>" failed, so
that a specific warning about that can be sent, different to the message when a
callout "RCPT TO:" fails. I think this is in fact now mostly done.
------------------------------------------------------------------------------

(129) 09-Jan-03 M  Keep track of DNSBL timeouts, and refrain from calling

If so configured, keep track of DNSBL timeouts in a hints record, and don't
retry that DNSBL for a while after (a sufficient number of) timeouts. It is
effectively disabled for a while. Log enable/disable, of course. Another
thought is an option not to apply +defer_unknown unless *all* DNSBL lookups in
a list defer.
------------------------------------------------------------------------------

(130) 09-Jan-03 M  A number of LDAP-related things
Peter A. Savitch

OpenLDAP 2.1 is going to be more popular (2.1.9 is available with many
bug fixes). TLS-enabled LDAP is an interesting and usefull thing.
I can try to implement some things and send the patches, like with
ldapi.

How do You see:

1) The propagation of TLS options (key, certificate, CA certificate)
   to the OpenLDAP library.

2) (was dereferencing; done in 4.23).
------------------------------------------------------------------------------

(131) 09-Jan-03 S  Additional variables
Peter A. Savitch

$root_uid    Why?

(Some that were previously here are done)

$smtp_accept_count    -- used for acl_smtp_connect

$queue_runners        -- children of the listening daemon could use this
                         value for controlling the number of queue runners

I don't like either of these because they cannot be real-time values. They
would be snapshots of the values at the time the process was forked from the
daemon, and I fear they would just be confusing. For processes that were not
forked from the daemon they couldn't be set at all.
------------------------------------------------------------------------------

(131) 09-Jan-03 S  Additional options
Peter A. Savitch

exim_processes_max
exim_file_descriptors_max
queue_run_condition   -- to deprecate queue_run_max, better system
                         load control

Given Exim's distributed nature, I'm not at all sure how the first two of these
can usefully be implemented.
------------------------------------------------------------------------------

(132) 16-Jan-03 M  Option for when a transport filter fails (crashes)

Freezing is one obvious option. Currently, Exim just retries. Another user
wanted to retry without the filter, but that is much harder.
------------------------------------------------------------------------------

(136) 24-Jan-03 M  Make "personal" available as a condition for use in routers
------------------------------------------------------------------------------

(138) 28-Jan-03 M  A variable containing what was matched in a host list

Or, presumably, other lists. This is so that ACL messages can say things like
"your host name matches xxxx". Note: not the same as $domain_data. Also, this
could be tricky with lookups and things that match in files.
------------------------------------------------------------------------------

(143) 06-Mar-03 L  Ability to have multiple authenticators of same type

For example, to have two PLAIN authenticators; if the first fails, try the
second.
------------------------------------------------------------------------------

(144) 07-Mar-03 T  ACL control = local_scan_skip to skip the local scan

A bigger project would be control = local_scan <xxx> where xxx could select
different local_scan functions (possibly by dynamic loading).

This can now be simulated using the fact that ACL variables are preserved,
so it doesn't look as it once did.
------------------------------------------------------------------------------

(145) 07-Mar-03 T  Export string_cat() to local_scan()
------------------------------------------------------------------------------

(147) 17-Mar-03 T  Option to treat 5xx as 4xx if received on initial connection

This issue is controversial. That may be a good reason for not changing
anything.
------------------------------------------------------------------------------

(153) 25-Apr-03 S  A way of making log_as_local apply to the smtp transport

Either an option on the transport, or log_remote_as_local for the router.
Messy, either way. Maybe log_local_as_local and log_remote_as_local, and
deprecate log_as_local?
------------------------------------------------------------------------------

(154) 01-May-03 M  Teergrubing at the CR/LF level

It is believed that the most effective way to teergrube is to insert a delay
between transmitting CR and LF in the SMTP response. Furthermore, this is also
the best place to test for bad synchronization (i.e. at the last possible
time).
------------------------------------------------------------------------------

(155) 01-May-03 S  "control=no_pipelining" for connect and EHLO ACLs

Yet more flexibility! Maybe this should be a more general control for what is
sent in response to EHLO.
------------------------------------------------------------------------------

(156) 06-May-02 M  Finer-grained synchronisation checking

On operating systems that can be asked whether any sent bytes have not yet been
ACK'd at the TCP/IP level, a finer-grained check for proper synchronisation can
be done. All bytes must have been ACK'd if the client has received the previous
response before sending the next command. See also 293.
------------------------------------------------------------------------------

(157) 07-May-03 M  Newline as a list item separator

This will make life easier for lists obtained form databases where the
separator is naturally a newline.
------------------------------------------------------------------------------

(158) 13-May-03 M  Ability to add to OK message for SMTP commands

For sending reasons for slow response, etc.
------------------------------------------------------------------------------

(160) 19-May-03 M  Remove headers using wild cards
------------------------------------------------------------------------------

(162) 28-May-03 M/L Use of real numbers in filters, expansions, and options

The motivation for this is for handling spam scores that are real numbers. The
questions are (a) how widely should it spread and (b) whether floating point or
fixed point representations should be used. And what about the eval operator?
------------------------------------------------------------------------------

(164) 02-Jun-03 S  Set variables for interface and port in smtp transport

These could be useful for varying HELO data etc. See also several other
items about interfaces above.
------------------------------------------------------------------------------

(166) 18-Jun-03 S  CN verification in client TLS code

A tls_verify_cn option is suggested by Sven Geggus.
------------------------------------------------------------------------------

(168) 19-Jun-03 S  Ability to add a header recording envelope rewrites

Current code adds a deleted header with only some information. Maybe what is
needed is a flag for a rewrite rule.
------------------------------------------------------------------------------

(169) 19-Jun-03 M  A way of detecting timeouts in callout returns

------------------------------------------------------------------------------

(170) 23-Jun-03 S  Option to accept rather than defer after local scan timeout

Suggested patch supplied.
------------------------------------------------------------------------------

(171) 23-Jun-03 S  Option to make timeout a soft failure on pipe transport

------------------------------------------------------------------------------

(172) 23-Jun-03 M  Option to make SQL query to specific server

------------------------------------------------------------------------------

(175) 04-Jul-03 S  show_all_ancestors_in_errmsg for the redirect router

This is the opposite of hide_child_in_errmsg in effect.
------------------------------------------------------------------------------

(180) 14-Jul-03 M  Extend never_users to be more flexible

e.g. never_users = ! mailnull : ! cyrus : !mailman : 0-100
------------------------------------------------------------------------------

(183) 16-Jul-03 S  freeze_tell_text to add custom text to the message

------------------------------------------------------------------------------

(185) 24-Jul-03 S  An expansion operator that decodes RFC 2047 strings

------------------------------------------------------------------------------

(188) 13-Aug-03 T  batch_max=0 to mean unlimited

------------------------------------------------------------------------------

(189) 22-Aug-03 S  Allow filter "logwrite" to write to syslog

I feel this is a dangerous facility, and also of very minority interest, at
least for user's filters. Allowing a system filter to write to mainlog or
syslog may be different. However, writing the main log would only be possible
if the filter runs as root or exim.
------------------------------------------------------------------------------

(190) 22-Aug-03 S  A way of testing "forced delivery" in filter and routers
------------------------------------------------------------------------------

(191) 26-Aug-03 M  Preserve $address_data for a verified recipient

The idea is to preserve it in the recipients data structure so that local_scan
can have access to it. The value could also be used as the initial value of
$address_data while routing.
------------------------------------------------------------------------------

(192) 05-Sep-03 M  Better handling of TXT records for dnslists

When multiple lists are accessible via a merged lookup, handling TXT records
is difficult. An option for doing the TXT lookup in a sub-list has been
suggested, with syntax such as

        dnslists = list.example.org=127.0.0.2%dialups \
                                   ,127.0.0.3%relays \
                                   ,127.0.0.5%spews
------------------------------------------------------------------------------

(194) 10-Sep-03 M  $addresslist_data to be like $host_data/$domain_data

------------------------------------------------------------------------------

(195) 29-Sep-03 M  A variable containing the error for verify = header_syntax

Maybe there should always be a variable with the error message for all the
different kinds of verify failure.
------------------------------------------------------------------------------

(196) 30-Sep-03 S  A way of detecting whether it was HELO or EHLO in the ACL

$received_protocol isn't reset until after the command is accepted (which
seems right), and $smtp_data shows only the arguments. Maybe $smtp_command?
------------------------------------------------------------------------------

(197) 30-Sep-03 S  MACROS_DROP_PRIVS and ALT_CONFIG_DROP_PRIVS

Now that alternative configurations can be restricted to certain directories,
some more flexibility can be allowed. Not by default, though.
------------------------------------------------------------------------------

(198) 01-Oct-03 M  Accept mail after local_scan() crash instead of defer

This may not be as easy to implement as it sounds; one is never sure of the
environment after a crash. Is is actually a good idea? The crashing local_scan
may have wrecked the memory in arbitrary ways; for example, screwing up the
recipients list...
------------------------------------------------------------------------------

(199) 01-Oct-03 M  ${pipe which will pipe the message to a script ...

... and otherwise behave as ${run. Probably needs to have locking out features
so that it can be turned off for users .forwards if the sysadmin so desires.
------------------------------------------------------------------------------

(200) 07-Oct-03 L  Alternative ways of storing hints

People want to store hints in databases. Some assert that SQL databases can
be made to perform satisfactorily. If a general interface could be worked on,
people could at least try different strategies. See also 66 above, which is
specifically concerned with Berkeley DB. Another possible option is a switch to
disable smtp-wait hints - to avoid contention problems.
------------------------------------------------------------------------------

(201) 07-Oct-03 M  A "soft bounce" feature

This is an option that turns all hard bounces into soft bounces. The idea is
that it can be used as a safety-net while testing configurations. Instead of a
local bounce, the message stays on the queue; instead of 5xx SMTP responses,
4xx ones are given.

The ability to do the opposite - turn 4xx into 5xx under certain circumstances
might also be useful (e.g. after a certain time). This might best be done by
extending the retry logic to recognize 4xx as a special error. (This is now
done.)
------------------------------------------------------------------------------

(202) 10-Oct-03 S  -bvsomething to do a callout after the verify

For example: -bvc and -bvsc. The problem now (Nov 04) is that there are quite a
few possible callout options that can be specified in an ACL, and they would
have to be replicated here.
------------------------------------------------------------------------------

(203) 14-Oct-03 S  verify=something to easily check for header presence

This is purely cosmetic; "condition" can already be used.
------------------------------------------------------------------------------

(204) 27-Oct-03 S  an inverted queue_only_file

That is, queue if a file does NOT exist.
------------------------------------------------------------------------------

(205) 27-Oct-03 S  expand smtp_accept_queue_per_connection

------------------------------------------------------------------------------

(206) 27-Oct-03 S  appendfile: a variable containing the maildir base name

------------------------------------------------------------------------------

(207) 29-Oct-03 S  ability to keep trusted users in a file - expand it.
------------------------------------------------------------------------------

(208) 31-Oct-03 M  cache temporary verification errors and fail after a time

This request was for a way of turning temporary verification failures into
permanent ones after some fixed time.
------------------------------------------------------------------------------

(209) 31-Oct-03 S  a way of making crashes in pipe commands temporary errors

------------------------------------------------------------------------------

(210) 31-Oct-03 S  runtime option to change the daemon name used for tcprwappers

A patch for compile time was supplied, but this seems better as a runtime
option, for use with multiple Exim daemons.
------------------------------------------------------------------------------

(211) 31-Oct-03 S  ability to disable debugging output from -bh & -bhc
------------------------------------------------------------------------------

(212) 31-Oct-03 M  specify headers lines in HELO ACL to be added to all msgs
------------------------------------------------------------------------------

(214) 05-Nov-03 S  Put the wild part of local part prefix/suffx in variables

Unfortunately, this isn't quite as trivial as it seems.
------------------------------------------------------------------------------

(215) 14-Nov-03 S  A way of turning off message-submission fix-ups

Globally, and perhaps also via an ACL control so that it can be done on a
per-message basis. Is this still needed? Since this item was added to this
list, default fixups for non-local messages have been removed, and control =
submission has been added.
------------------------------------------------------------------------------

(215) 26-Nov-03 M/L Conversion of IDNA domain names for logging

IDNA (RFCs 3490-3492) converts domains names containing non-ASCII characters
into ASCII strings of a special form. Exim will of course handle these.
However, it might be nice to convert them to a local code for logging. This
might be quite a big project: there's also output from -bp and eximon queue
display and no doubt other places as well. (Utilities that process the logs,
e.g. exigrep, eximstats, will be automatically handled if the logs are
changed.)
------------------------------------------------------------------------------

(216) 27-Nov-03 S  Option to bounce if required TLS doesn't happen

This is for the smtp transport with hosts_require_tls set. Currently, it
defers. Possibly the best approach is to make the error one that can be seen by
the retry logic.
------------------------------------------------------------------------------

(217) 27-Nov-03 M  A function to pass back variables from Perl

This is a function that can be called from Perl, to take a name and a value and
put that value into an Exim variable.
------------------------------------------------------------------------------

(218) 01-Dec-03 M  A local_scan-like hook at system filter time

That is, make a C API available for custom filtering at this point.
------------------------------------------------------------------------------

(221) 18-Dec-03 U  Merge routers and ACLs - or at least make more similar

"It will be very useful to be able to use most of the ACL conditions
(authenticated, hosts, senders, sender_domains, ... ) in routers and also the
possibility to have multiple conditions in routers. It will be great to also
be able to set variables in routers like in acl's." This is effectively a
radical suggestion for a complete re-design, and is therefore BIG.
------------------------------------------------------------------------------

(223) 22-Dec-03 S  Support SOA lookup in dnsdb lookups

This could be like zns, and climb up the tree till it hits a zone. Would the
name of the zone be required?
------------------------------------------------------------------------------

(225) 22-Dec-03 M  Add acl= to routers

This would use an ACL to "control access" to a router, opening up a number
of interesting possibilities. Details of possible limitations need to be
investigated.
------------------------------------------------------------------------------

(226) 23-Dec-03 S  A way of treating DEFER as fail in dnsdb lookups

(i.e. the dnsdb lookup failed, so accept the message)
------------------------------------------------------------------------------

(227) 30-Jan-04 M  A configuration .if facility

"Second with the .ifdef and such, it would be nice to have a base .if,
so I could do something like
.if DEFINED_DATA == xyz
configuration here
.elseif DEFINED_DATA == abc
configuration here
.else
configuration here
.endif
also this would be nice at least in my case in the system filters, but
isn't required but you could pass the defined data to the system, in
variables."
------------------------------------------------------------------------------

(229) 30-Jan-04 M  New expansion mechanism: {list ...}

"Proposed syntax: {list {separator}{item}{item}...}
This first expands the contents of {separator} and all of the {item}s,
then constructs a separator-delimited list. The twist is: if an {item}
generates the empty string, no separator will be generated for it.
The entire construct will fail is {separator} fails, or all {item}s
fail. If just some {item}s fail, they will be treated as if they
generated empty strings.
Examples:
   {list {,}{aaaaaa}{bbbbbb}{cccccc}} -> aaaaaa,bbbbbb,cccccc
   {list {,}{:fail:}{bbbbbb}{cccccc}} -> bbbbbb,cccccc
   {list {,}{aaaaaa}{:fail:}{cccccc}} -> aaaaaa,cccccc
   {list { }{aaaaaa}{bbbbbb}{}}       -> aaaaaa bbbbbb
   {list { }{:fail:}{:fail:}{:fail:}} -> :fail:
   {list {:fail:}{aaaaa}{bbbb}{cccc}} -> :fail:
See particularly examples 2-4, which handle the case of a missing first
and last item with ease; doing this using {if ...} would be quite difficult!"
------------------------------------------------------------------------------

(230) 30-Jan-04 M  Find IP addresses of a domain's nameservers

This needs some way of processing a list of things in a similar way, which
should perhaps be a more general facility. // This can now be done using the
list facilities of dnsdb; verbose, but it can be done. //
------------------------------------------------------------------------------

(231) 30-Jan-04 ?  -C has a number of problems when used for real

-C was intended for testing; people are using it for "alternate"
configurations, and it doesn't work too well. Can a better way of doing this be
invented?
------------------------------------------------------------------------------

(232) 02-Feb-04 ?  Make parts of the code loadable

The idea being that drivers, etc. could be compiled separately. There are, of
course, security issues. This is not something I want to go into at present.
------------------------------------------------------------------------------

(235) 02-Feb-04 T  Make smtp_accept_count available as a variable

This is for use in ACLs. Of course, it is a snapshot of the count at the
start of the receiving process. As such, it could be confusing because if a
connection lasts a long time, the "true" value could be very different. For
this reason, I don't really like this idea.
------------------------------------------------------------------------------

(236) 02-Feb-04 S  String in local_scan that's added to the binary version string
------------------------------------------------------------------------------

(237) 02-Feb-04 M  Add_header in ACLs because "message" is overloaded

This would be useful for verbs where "message" is an error message.
------------------------------------------------------------------------------

(238) 05-Feb-04 S  ${address to handle multiple addresses

At present, ${address expects to see just one address. An extension would let
it handle header lines with multiple addresses, just retaining the actual
addresses. Or perhaps a new operator is needed?
------------------------------------------------------------------------------

(239) 23-Feb-04 ?  Expansion items for encryption/decryption

Perhaps for some kind of cookie handling? This would need an external crypto
library, because there's no crypto code in Exim itself.
------------------------------------------------------------------------------

(240) 23-Feb-04 ? Some way to know if a ip is a mx for a given domain

Some kind of iterative operation for dnsdb might be a general way of providing
this. // This can now be done using the list facilities of dnsdb; verbose, but
it can be done. //
------------------------------------------------------------------------------

(242) 01-Mar-04 ? Run a filter from an expansion condition

This would add a lot of power to ACLs, but its implementation might be tricky
because of the possibility of recursion.
------------------------------------------------------------------------------

(243) 01-Mar-04 ? Run an ACL from an expansion condition

The problem here is knowing what data is available at an arbitrary time.
------------------------------------------------------------------------------

(244) 01-Mar-04 ? Add an on-success event to transports

This could just be an expansion string, whose value is either ignored or
logged, but it could be used to run SQL updates or run programs etc.
However, what is "success" when a transport has multiple recipients?
------------------------------------------------------------------------------

(245) 01-Mar-04 M Add all the string expansion conditions to filters

Some thought would be needed on how to design the syntax for this.
------------------------------------------------------------------------------

(247) 09-Mar-04 S IP addresses that are never looked up

It would be nice if we could prevent this for certain IP addresses for
which we _know_ we'll never get a valid PTR record, like 2002::/16.
So a new option might reasonably default to:

        hosts_never_lookup = <; 2002::/16
------------------------------------------------------------------------------

(253) 05-Apr-04 M Use ESMTP and TLS for recipient callout verification

The best way to do this would involve quite a bit of refactoring so as to
abstract some of the code from the smtp transport into subroutines that could
also be used from the callout code. The tls parameters should probably be
taken from the transport. That might also require some substantial code
refactoring. See also 294.
------------------------------------------------------------------------------

(260) 30-Apr-04 S Respect +tls_cipher +tls_peerdn in rejectlog entries

------------------------------------------------------------------------------

(261) 05-May-04 S Add a "required_version" option

So that configurations can insist on a specific Exim version.
------------------------------------------------------------------------------

(262) 10-May-04 S Add "scratch" ACL variables

The idea is for variables that are flushed at the start of each ACL. I'm not
really convinced that these are worth implementing.
------------------------------------------------------------------------------

(263) 10-May-04 S Add variable $router_name $transport_name

These could be used in debug_print settings, which are output during -bt, and
thus don't need the privilege to run with -d.
------------------------------------------------------------------------------

(265) 25-May-04 M An init.d script for exim is needed

The old sendmail script used to "just work" because it just did -bd -q 20m or
whatever. Newer versions start more than one sendmail daemon, so do not work.
------------------------------------------------------------------------------

(267) 25-May-04 S tarpitting delay option

A modifier that sets a delay between lines for multiline responses.
------------------------------------------------------------------------------

(268) 25-May-04 S? Add a PID to every log line

Given that pids are reused non-cyclically these days, is this actually useful?
------------------------------------------------------------------------------

(270) 01-Jun-04 M Add headers at top and middle

Various initiatives like SPF and DomainKeys require header lines to be added
above or in the middle of existing headers. Exim always adds at the bottom.
When these requirements are more standard and clearer, some way of controlling
where header lines are added will probably become necessary. Some new syntax
will be required.

This can now be done fairly generally from local_scan(), and at the start and
after the Received: block from an ACL. Is anything more needed?
------------------------------------------------------------------------------

(271) 02-Jun-04 L Callouts at routing time

From a user's message:

> I would like to be able to:
>[...]
> 2) Forcing callouts as address verification at router level
> [ check_callout just like check_local_user ]
>
> I would like to redirect messages in some domain to "domain with callout
> verification" and to "domain without callout verification"
>
> e.g.
> userA@domain.in -> userX@doamin.out-verify (use callout to verify)
> userB@domain.in -> userY@doamin.out-noverify (do not use callout verify)
>
> [both out-* domains delivered via "callout ready" transports]

Other versions of the wish:
* limiting callouts in acls to specific transport
      verify = recipient/callout=5s,transport:intranet_smtp
* adding "select transport" to ACL conditions
      accept domains = +local_domains
             transport = cyrus_ltcp
             verify = recipient/callout=5s
------------------------------------------------------------------------------

(272) 07-Jun-04 S Expand hosts_randomize

It occurs in manualroute and in smtp.
------------------------------------------------------------------------------

(278) 21-Jun-04 M quota_warn_message_file option

Similar to the bounce and delivery warn message files.
------------------------------------------------------------------------------

(280) 23-Jun-04 M A way of adding a header line after callout defer_ok

This would record that, e.g., a sender domain verified, but the callout
could not be done. There are ways of fudging this, using ACL variables and
"warn" statements.
------------------------------------------------------------------------------

(285) 16-Jul-04 M Separate and independent log_selector for rejectlog

For example: mainlog_selector and rejectlog_selector, with log_selector setting
both of them.
------------------------------------------------------------------------------

(286) 21-Jul-04 M Distinguishing a larger number of errors

For instance, detecting "connection reset by peer" (ENETRESET or ECONNRESET)
might be useful.
------------------------------------------------------------------------------

(288) 10-Aug-04 M Option for verify to require MX

e.g. verify=sender/require_mx
I'm not too keen because this is rather special purpose, and of course could
only apply if the verification happened to hit a dnslookup router.
------------------------------------------------------------------------------

(289) 10-Aug-04 L Option to treat defers in database lookups as "not found"

This is so that alternatives can be coded for when databases are down. A
suggested patch has been sent, but it just catches all instances of "defer"
from a lookup in an expansion string. These can occur for a number of different
reasons, not just connection failures. I think that we need a specific
"connection failed" indicator. Also, what about lookups in lists?
------------------------------------------------------------------------------

(291) 13-Aug-04 M An ACL or "local_scan()" to be run on size excession

The idea is to give something a chance to look at the data so far received when
more than message_size_limit (or some other limit) has arrived. I am not sure
how useful this would actually be in practice.
------------------------------------------------------------------------------

(292) 13-Aug-04 M Overall timeout for message reception

A client could in priciple keep an SMTP connection open for a very long time by
trickling in data very slowly. Also, after message_size_limit is exceeded, Exim
continues to swallow the data (though it does not write it to disk) until the
end is reached. Again, the connection could be held open for a very long time.
Some kind of overall time limit for an SMTP connection, possibly reset at the
start of each message, might be helpful in these situations.
------------------------------------------------------------------------------

(294) 23-Aug-04 L Callouts and AUTH and LMTP

People want to do callouts using LMTP as well as SMTP, and that would also
include sockets as well as TCP/IP connections. Also, people want to make use of
AUTH during the callout checking, on all types of connection. I suppose that
means making TLS available as well. This probably means a rewrite of the code
that actually does the callout. Should we use the relevant transport in a new
"callout" mode instead of keeping things separate? See also 253 and 323.

And here's another submitted idea: "My actual suggestion is that if this model
is followed, the parent process doesn't have to stop the callout process if it
is taking too long to respond: it can return 450 to the incoming connection
within the 5 minute SMTP command timeout and leave the callout process to
continue, in the hope that it will eventually get a result and store it in the
callout cache in time for the sender's next attempt."
------------------------------------------------------------------------------

(296) 09-Sep-04 S Make deliver_time work for == lines as well as =>

What about ** lines?
------------------------------------------------------------------------------

(299) 25-Oct-04 S Options to make Sieve "keep" pass to next router

Currently, "keep" saves in the mailbox. Probably need two options, for implicit
and explicit keep commands.
------------------------------------------------------------------------------

(301) 27-Oct-04 M Use an "ACL" to filter logging

This idea was for ACL syntax to be able to "accept" or "deny" individual log
lines. This would make it possible to have, for example, per-host logging for
certain things. See also 15 above.
------------------------------------------------------------------------------

(302) 28-Oct-04 M Expand pass_router and redirect_router

Doing this would mean postponing the validity checks till the router was
actually used instead of doing them at start up. It does not seem to be a
facility that will be widely used.
------------------------------------------------------------------------------

(303) 28-Oct-04 M Support SQL relay

This would make it easier for packagers to support "generic SQL" without having
to choose which one. It can be slotted in using a MySQL interface without
modifying Exim, but native support would be nice.
------------------------------------------------------------------------------

(304) 02-Nov-04 M A way of seeing the whole message in Perl or ${run

At present, the headers are available in $message_headers, but only part of
the body is visible. The only way to pass the whole body would be as a file
descriptor because it can be very large. See also (42).
------------------------------------------------------------------------------

(305) 02-Nov-04 M A Perl transport

The suggestion here is that an embedded Perl function takes responsibility for
doing the delivery. I am not at all keen on this. One way of doing it would be
to implement (244), which provides an "on success" string expansion. Then
anyone who wants this could run that on a transport that does nothing.
------------------------------------------------------------------------------

(306) 09-Nov-04 M Make the search type partial-lsearch*@ be useful

At present, it treats the whole key as a domain for the partial search, then
does the *@ thing. A more sensible plan would be something like:

  user@company.com
  *@company.com
  user@*.company.com
  *@*.company.com
  *

That is, try the local part and * at each of the partial domain values.
------------------------------------------------------------------------------

(307) 24-Nov-04 S Check the syntax of Message-ID: header lines

This could be added to "verify=header_syntax" or, if the incompatibility is
felt to be too great, an additional condition, or a sub-option, could be added.
------------------------------------------------------------------------------

(308) 24-Nov-04 S Add $body_longlinecount and $header_longlinecount

These variables would hold the number of physical lines in the body and header
that were longer than 998 bytes. This would be fiddly to implement because of
the way Exim currently reads the input. It isn't just a trivial patch.
------------------------------------------------------------------------------

(309) 01-Dec-04 S/M Queue runners should get locks before forking

If a queue-runner opened the -D file and took out the lock before forking, it
would waste fewer resources if the message was already being delivered. But how
often would this actually matter in practice?
------------------------------------------------------------------------------

(310) 06-Dec-04 S After "personal" save what matched

The idea is to save the email address that actually was found in the message
in a variable so it can be used (e.g. as the From: address in an autoreply).
------------------------------------------------------------------------------

(311) 07-Dec-04 ? More flexible SMTP response codes

The requestor wanted to be able to specify, for example, 551 in an ACL deny
instead of 550, and also vary the defer code. The first digit, however, should
remain fixed. In addition to main codes, enhanced status codes (RFC 2034) were
requested. (As far as I can tell, they have never been highly popular.)
------------------------------------------------------------------------------

(312) 10-Dec-04 ? Shadow remote transports

Unless a lot of work is done, this would be restricted to another remote
transport. A similar effect could therefore be achieved with "shadow_hosts"
which are like fallback_hosts but which operate on success.
------------------------------------------------------------------------------

(313) 21-Jan-05 ? Multiple queues

Exim runs poorly if its queue gets too big. Various ways round this are all
to some extent kludges. There has been a suggestion of using multiple
directories instead of just "input". (Originally it was for a whole set of
spool directories, but that introduces complications with the hint files.)
On message arrival, somehow a selection of "input" must be made. Then queue
runners must be startable for the different "queues". Don't forget that the
"msglog" directory is also involved. Perhaps add a new level of indirection:
/var/spool/exim/queue1/{input,msglog}, /var/spool/exim/queue2/....
------------------------------------------------------------------------------

(314) 15-Feb-05 M Multiple headers_{add,remove} for routers

If headers_{add,remove} could be specified multiple times, it would be easier
for those people that construct configs using .ifdef or .include, etc.
------------------------------------------------------------------------------

(315) 15-Feb-05 M String variables for use in filters.

Currently, only numerical variables are supported.
------------------------------------------------------------------------------

(316) 21-Feb-05 M Put callout response into a variable

When a callout fails, put the entire SMTP response into a variable. This is not
trivial because we probably should retain it in the cache as well.
------------------------------------------------------------------------------

(317) 25-Feb-05 S Delete the pid file when the daemon exits

At least try to catch some of the exit routes from the daemon and either delete
or empty the pid file.
------------------------------------------------------------------------------

(318) 02-Mar-05 S Add current connection count to daemon's exiwhat output
------------------------------------------------------------------------------

(319) 03-Mar-05 ? Allow file rather than directory for scanning call

"I can call arbitrary scanning software by specifying the full path. I can pass
a directory to be scanned in the arguments. I'd like to be able to pass a
specific file name instead of a directory. I think this would allow me to call
Bogofilter at smtp time. Bogofilter requires a filename, not a directory. The
file would contain the complete email. I suppose there may be other scanning
solutions with a similar requirement."
------------------------------------------------------------------------------

(320) 03-Mar-05 T Options to control daemon retry binding

Currently the daemon tries 10 times at 30-second intervals to listen on an IP
address. The wish is for options to control these numbers.
------------------------------------------------------------------------------

(321) 07-Mar-05 S Run an ACL on a sync error

... and possibly "accept" or "deny" it.
------------------------------------------------------------------------------

(322) 15-Mar-05 M Add a /defer_ok option to verify=reverse_host_lookup
------------------------------------------------------------------------------

(323) 15-Mar-05 M Make callouts use smtp_data from the smtp transport

This is yet another problem caused by duplicating the SMTP code between the
transport and the callout verification. See item 294 above. Merging the
transport and the callout code could prevent this kind of thing from happening.
------------------------------------------------------------------------------

(324) 04-Apr-05 ? Make -bP show ACLs

This is in the Bugzilla as #10.
------------------------------------------------------------------------------
--- HWM 324 ------------------------------------------------------------------
---------------------------- End of WishList ---------------------------------