Docs: add known broken-version info for OpenSSL behavior

[users/heiko/exim.git] / doc / doc-docbook / spec.xfpt

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index 16d276ee8503f11b84997eccb1266c3e41c65436..d8f1573c93cea545a80095b0fed783a0b9f37a7d 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -448,12 +448,11 @@ available in other formats (HTML, PostScript, PDF, and Texinfo). Section
 .section "FTP and web sites" "SECID2"
 .cindex "web site"
 .cindex "FTP site"
 .section "FTP and web sites" "SECID2"
 .cindex "web site"
 .cindex "FTP site"

-The primary site for Exim source distributions is currently the University of
-Cambridge's FTP site, whose contents are described in &'Where to find the Exim
-distribution'& below. In addition, there is a web site and an FTP site at
-&%exim.org%&. These are now also hosted at the University of Cambridge. The
-&%exim.org%& site was previously hosted for a number of years by Energis
-Squared, formerly Planet Online Ltd, whose support I gratefully acknowledge.
+.new
+The primary site for Exim source distributions is the &%exim.org%& FTP site,
+available over HTTPS, HTTP and FTP.  These services, and the &%exim.org%&
+website, are hosted at the University of Cambridge.
+.wen

 
 .cindex "wiki"
 .cindex "FAQ"
 
 .cindex "wiki"
 .cindex "FAQ"


@@ -462,12 +461,18 @@ differently formatted versions of the documentation. A recent addition to the
 online information is the Exim wiki (&url(http://wiki.exim.org)),
 which contains what used to be a separate FAQ, as well as various other
 examples, tips, and know-how that have been contributed by Exim users.
 online information is the Exim wiki (&url(http://wiki.exim.org)),
 which contains what used to be a separate FAQ, as well as various other
 examples, tips, and know-how that have been contributed by Exim users.

+.new
+The wiki site should always redirect to the correct place, which is currently
+provided by GitHub, and is open to editing by anyone with a GitHub account.
+.wen

 
 .cindex Bugzilla
 An Exim Bugzilla exists at &url(https://bugs.exim.org). You can use
 this to report bugs, and also to add items to the wish list. Please search
 first to check that you are not duplicating a previous entry.
 
 .cindex Bugzilla
 An Exim Bugzilla exists at &url(https://bugs.exim.org). You can use
 this to report bugs, and also to add items to the wish list. Please search
 first to check that you are not duplicating a previous entry.

-
+.new
+Please do not ask for configuration help in the bug-tracker.
+.wen

 
 
 .section "Mailing lists" "SECID3"
 
 
 .section "Mailing lists" "SECID3"


@@ -505,26 +510,45 @@ message to the &'exim-dev'& mailing list and have it discussed.
 
 .section "Where to find the Exim distribution" "SECTavail"
 .cindex "FTP site"
 
 .section "Where to find the Exim distribution" "SECTavail"
 .cindex "FTP site"

+.cindex "HTTPS download site"

 .cindex "distribution" "ftp site"
 .cindex "distribution" "ftp site"

-The master ftp site for the Exim distribution is
+.cindex "distribution" "https site"
+.new
+The master distribution site for the Exim distribution is

 .display
 .display

-&*ftp://ftp.exim.org/pub/exim*&
+&*https://downloads.exim.org/*&

 .endd
 .endd

-The file references that follow are relative to the &_exim_& directories at
-these sites. There are now quite a number of independent mirror sites around
+The service is available over HTTPS, HTTP and FTP.
+We encourage people to migrate to HTTPS.
+
+The content served at &'https://downloads.exim.org/'& is identical to the
+content served at &'https://ftp.exim.org/pub/exim'& and
+&'ftp://ftp.exim.org/pub/exim'&.
+
+If accessing via a hostname containing &'ftp'&, then the file references that
+follow are relative to the &_exim_& directories at these sites.
+If accessing via the hostname &'downloads'& then the subdirectories described
+here are top-level directories.
+.wen
+
+There are now quite a number of independent mirror sites around

 the world. Those that I know about are listed in the file called &_Mirrors_&.
 
 the world. Those that I know about are listed in the file called &_Mirrors_&.
 

-Within the &_exim_& directory there are subdirectories called &_exim3_& (for
+Within the top exim directory there are subdirectories called &_exim3_& (for

 previous Exim 3 distributions), &_exim4_& (for the latest Exim 4
 distributions), and &_Testing_& for testing versions. In the &_exim4_&
 subdirectory, the current release can always be found in files called
 .display
 previous Exim 3 distributions), &_exim4_& (for the latest Exim 4
 distributions), and &_Testing_& for testing versions. In the &_exim4_&
 subdirectory, the current release can always be found in files called
 .display

+&_exim-n.nn.tar.xz_&

 &_exim-n.nn.tar.gz_&
 &_exim-n.nn.tar.bz2_&
 .endd
 &_exim-n.nn.tar.gz_&
 &_exim-n.nn.tar.bz2_&
 .endd

-where &'n.nn'& is the highest such version number in the directory. The two
+where &'n.nn'& is the highest such version number in the directory. The three

 files contain identical data; the only difference is the type of compression.
 files contain identical data; the only difference is the type of compression.

-The &_.bz2_& file is usually a lot smaller than the &_.gz_& file.
+.new
+The &_.xz_& file is usually the smallest, while the &_.gz_& file is the
+most portable to old systems.
+.wen

 
 .cindex "distribution" "signing details"
 .cindex "distribution" "public key"
 
 .cindex "distribution" "signing details"
 .cindex "distribution" "public key"


@@ -538,17 +562,16 @@ PGP key, a version of which can be found in the release directory in the file
 &_nigel-pubkey.asc_&.  All keys used will be available in public keyserver pools,
 such as &'pool.sks-keyservers.net'&.
 
 &_nigel-pubkey.asc_&.  All keys used will be available in public keyserver pools,
 such as &'pool.sks-keyservers.net'&.
 

-At time of last update, releases were being made by Phil Pennock and signed with
-key &'0x403043153903637F'&, although that key is expected to be replaced in 2013.
-A trust path from Nigel's key to Phil's can be observed at
-&url(https://www.security.spodhuis.org/exim-trustpath).
-
-Releases have also been authorized to be performed by Todd Lyons who signs with
-key &'0xC4F4F94804D29EBA'&. A direct trust path exists between previous RE Phil
-Pennock and Todd Lyons through a common associate.
+.new
+At time of last update, releases were being made by Jeremy Harris and signed
+with key &'0xBCE58C8CE41F32DF'&.  Other recent keys used for signing are those
+of Heiko Schlittermann, &'0x26101B62F69376CE'&,
+and of Phil Pennock, &'0x4D1E900E14C1CC04'&.
+.wen

 
 The signatures for the tar bundles are in:
 .display
 
 The signatures for the tar bundles are in:
 .display

+&_exim-n.nn.tar.xz.asc_&

 &_exim-n.nn.tar.gz.asc_&
 &_exim-n.nn.tar.bz2.asc_&
 .endd
 &_exim-n.nn.tar.gz.asc_&
 &_exim-n.nn.tar.bz2.asc_&
 .endd


@@ -566,8 +589,10 @@ inside the &_exim4_& directory of the FTP site:
 &_exim-postscript-n.nn.tar.gz_&
 &_exim-texinfo-n.nn.tar.gz_&
 .endd
 &_exim-postscript-n.nn.tar.gz_&
 &_exim-texinfo-n.nn.tar.gz_&
 .endd

+.new

 These tar files contain only the &_doc_& directory, not the complete
 These tar files contain only the &_doc_& directory, not the complete

-distribution, and are also available in &_.bz2_& as well as &_.gz_& forms.
+distribution, and are also available in &_.bz2_& and &_.xz_& forms.
+.wen

 
 
 .section "Limitations" "SECID6"
 
 
 .section "Limitations" "SECID6"


@@ -3838,7 +3863,7 @@ alternate queue is used, named by the following argument.
 .vitem &%-MCK%&
 .oindex "&%-MCK%&"
 This option is not intended for use by external callers. It is used internally
 .vitem &%-MCK%&
 .oindex "&%-MCK%&"
 This option is not intended for use by external callers. It is used internally

-by Exim in conjunction with the &%-MC%& option. It signifies that an
+by Exim in conjunction with the &%-MC%& option. It signifies that a

 remote host supports the ESMTP &_CHUNKING_& extension.
 
 .vitem &%-MCP%&
 remote host supports the ESMTP &_CHUNKING_& extension.
 
 .vitem &%-MCP%&


@@ -7846,7 +7871,7 @@ of which must be reachable from the running exim instance. If the cluster has
 master/slave replication, the list must contain all the master and slave
 servers.
 
 master/slave replication, the list must contain all the master and slave
 servers.
 

-When the Redis Cluster returns a "MOVED" response to a query, exim does not
+When the Redis Cluster returns a "MOVED" response to a query, Exim does not

 immediately follow the redirection but treats the response as a DEFER, moving on
 to the next server in the &%redis_servers%& list until the correct server is
 reached.
 immediately follow the redirection but treats the response as a DEFER, moving on
 to the next server in the &%redis_servers%& list until the correct server is
 reached.


@@ -9159,8 +9184,8 @@ This item returns a string suitable for insertion as an
 &'Authentication-Results"'&
 header line.
 The given <&'authserv-id'&> is included in the result; typically this
 &'Authentication-Results"'&
 header line.
 The given <&'authserv-id'&> is included in the result; typically this

-will ba a domain name identifying the system performing the authentications.
-Methods that may be present in the result include:
+will be a domain name identifying the system performing the authentications.
+Methods that might be present in the result include:

 .code
 none
 iprev
 .code
 none
 iprev


@@ -9173,7 +9198,7 @@ Example use (as an ACL modifier):
 .code
       add_header = :at_start:${authresults {$primary_hostname}}
 .endd
 .code
       add_header = :at_start:${authresults {$primary_hostname}}
 .endd

-This is safe even if no authentication reselts are available.
+This is safe even if no authentication results are available.

 .wen
 
 
 .wen
 
 


@@ -12972,7 +12997,8 @@ It is only useful as the argument of a
 &%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator,
 or a &%def%& condition.
 
 &%certextract%& expansion item, &%md5%&, &%sha1%& or &%sha256%& operator,
 or a &%def%& condition.
 

-&*Note*&: Under current versions of OpenSSL, when a list of more than one
+&*Note*&: Under versions of OpenSSL preceding 1.1.1,
+when a list of more than one

 file is used for &%tls_certificate%&, this variable is not reliable.
 
 .vitem &$tls_in_peercert$&
 file is used for &%tls_certificate%&, this variable is not reliable.
 
 .vitem &$tls_in_peercert$&


@@ -16966,10 +16992,10 @@ tests of Exim without using the standard spool.
 
 .option spool_wireformat main boolean false
 .cindex "spool directory" "file formats"
 
 .option spool_wireformat main boolean false
 .cindex "spool directory" "file formats"

-If this option is set, Exim may for some messages use an alternate format
+If this option is set, Exim may for some messages use an alternative format

 for data-files in the spool which matches the wire format.
 Doing this permits more efficient message reception and transmission.
 for data-files in the spool which matches the wire format.
 Doing this permits more efficient message reception and transmission.

-Currently it is only done for messages received using the EMSTP CHUNKING
+Currently it is only done for messages received using the ESMTP CHUNKING

 option.
 
 The following variables will not have useful values:
 option.
 
 The following variables will not have useful values:


@@ -16982,7 +17008,7 @@ $body_zerocount
 Users of the local_scan() API (see &<<CHAPlocalscan>>&),
 and any external programs which are passed a reference to a message data file
 (except via the &"regex"&, &"malware"& or &"spam"&) ACL conditions)
 Users of the local_scan() API (see &<<CHAPlocalscan>>&),
 and any external programs which are passed a reference to a message data file
 (except via the &"regex"&, &"malware"& or &"spam"&) ACL conditions)

-will need to be aware of the potential different format.
+will need to be aware of the different formats potentially available.

 
 Using any of the ACL conditions noted will negate the reception benefit
 (as a Unix-mbox-format file is constructed for them).
 
 Using any of the ACL conditions noted will negate the reception benefit
 (as a Unix-mbox-format file is constructed for them).


@@ -17212,7 +17238,8 @@ option in the relevant &(smtp)& transport.
 &*Note*&: If you use filenames based on IP addresses, change the list
 separator in the usual way to avoid confusion under IPv6.
 
 &*Note*&: If you use filenames based on IP addresses, change the list
 separator in the usual way to avoid confusion under IPv6.
 

-&*Note*&: Under current versions of OpenSSL, when a list of more than one
+&*Note*&: Under versions of OpenSSL preceding 1.1.1,
+when a list of more than one

 file is used, the &$tls_in_ourcert$& variable is unreliable.
 
 &*Note*&: OCSP stapling is not usable under OpenSSL
 file is used, the &$tls_in_ourcert$& variable is unreliable.
 
 &*Note*&: OCSP stapling is not usable under OpenSSL


@@ -26235,8 +26262,8 @@ deliver the message unauthenticated.
 
 Note that the hostlist test for whether to do authentication can be
 confused if name-IP lookups change between the time the peer is decided
 
 Note that the hostlist test for whether to do authentication can be
 confused if name-IP lookups change between the time the peer is decided

-on and the transport running.  For example, with a manualroute
-router given a host name, and DNS "round-robin" use by that name: if
+upon and the time that the transport runs.  For example, with a manualroute
+router given a host name, and with DNS "round-robin" used by that name: if

 the local resolver cache times out between the router and the transport
 running, the transport may get an IP for the name for its authentication
 check which does not match the connection peer IP.
 the local resolver cache times out between the router and the transport
 running, the transport may get an IP for the name for its authentication
 check which does not match the connection peer IP.


@@ -27229,7 +27256,7 @@ The history of port numbers for TLS in SMTP is a little messy and has been
 contentious.  As of RFC 8314, the common practice of using the historically
 allocated port 465 for "email submission but with TLS immediately upon connect
 instead of using STARTTLS" is officially blessed by the IETF, and recommended
 contentious.  As of RFC 8314, the common practice of using the historically
 allocated port 465 for "email submission but with TLS immediately upon connect
 instead of using STARTTLS" is officially blessed by the IETF, and recommended

-in preference to STARTTLS.
+by them in preference to STARTTLS.

 
 The name originally assigned to the port was &"ssmtp"& or &"smtps"&, but as
 clarity emerged over the dual roles of SMTP, for MX delivery and Email
 
 The name originally assigned to the port was &"ssmtp"& or &"smtps"&, but as
 clarity emerged over the dual roles of SMTP, for MX delivery and Email


@@ -27240,8 +27267,8 @@ standardized, but many clients kept using it, even as the TCP port number was
 reassigned for other use.
 Thus you may encounter guidance claiming that you shouldn't enable use of
 this port.
 reassigned for other use.
 Thus you may encounter guidance claiming that you shouldn't enable use of
 this port.

-In practice, a number of mail-clients have only supported submissions, not
-submission with STARTTLS upgrade.
+In practice, a number of mail-clients have only ever supported submissions,
+not submission with STARTTLS upgrade.

 Ideally, offer both submission (587) and submissions (465) service.
 
 Exim supports TLS-on-connect by means of the &%tls_on_connect_ports%&
 Ideally, offer both submission (587) and submissions (465) service.
 
 Exim supports TLS-on-connect by means of the &%tls_on_connect_ports%&


@@ -28139,6 +28166,9 @@ the entire certificate chain from CA to server-certificate.  If a public CA is u
 DANE-TA is commonly used for several services and/or servers, each having a TLSA query-domain CNAME record,
 all of which point to a single TLSA record.
 
 DANE-TA is commonly used for several services and/or servers, each having a TLSA query-domain CNAME record,
 all of which point to a single TLSA record.
 

+Another approach which should be seriously considered is to use DANE with a certificate
+from a public CA, because of another technology, "MTA-STS", described below.
+

 The TLSA record should have a Selector field of SPKI(1) and a Matching Type field of SHA2-512(2).
 
 At the time of writing, &url(https://www.huque.com/bin/gen_tlsa)
 The TLSA record should have a Selector field of SPKI(1) and a Matching Type field of SHA2-512(2).
 
 At the time of writing, &url(https://www.huque.com/bin/gen_tlsa)


@@ -28225,6 +28255,28 @@ The &$event_data$& will be one of the Result Types defined in
 Section 4.3 of that document.
 
 Under GnuTLS, DANE is only supported from version 3.0.0 onwards.
 Section 4.3 of that document.
 
 Under GnuTLS, DANE is only supported from version 3.0.0 onwards.

+
+DANE is specified in published RFCs and decouples certificate authority trust
+selection from a "race to the bottom" of "you must trust everything for mail
+to get through".  There is an alternative technology called MTA-STS, which
+instead publishes MX trust anchor information on an HTTPS website.  At the
+time this text was last updated, MTA-STS was still a draft, not yet an RFC.
+Exim has no support for MTA-STS as a client, but Exim mail server operators
+can choose to publish information describing their TLS configuration using
+MTA-STS to let those clients who do use that protocol derive trust
+information.
+
+The MTA-STS design requires a certificate from a public Certificate Authority
+which is recognized by clients sending to you.  That selection is outside your
+control.
+
+The most interoperable course of action is probably to use
+&url(https://letsencrypt.org/,Let's Encrypt), with automated certificate
+renewal; to publish the anchor information in DNSSEC-secured DNS via TLSA
+records for DANE clients (such as Exim and Postfix) and to publish anchor
+information for MTA-STS as well.  This is what is done for the &'exim.org'&
+domain itself (with caveats around occasionally broken MTA-STS because of
+incompatible specification changes prior to reaching RFC status).

 .wen
 
 
 .wen
 
 


@@ -29439,7 +29491,7 @@ and cannot depend on content of received headers.
 Note also that headers cannot be
 modified by any of the post-data ACLs (DATA, MIME and DKIM).
 Headers may be modified by routers (subject to the above) and transports.
 Note also that headers cannot be
 modified by any of the post-data ACLs (DATA, MIME and DKIM).
 Headers may be modified by routers (subject to the above) and transports.

-The Received-By: header is generated as soon as the body reception starts,
+The &'Received-By:'& header is generated as soon as the body reception starts,

 rather than the traditional time after the full message is received;
 this will affect the timestamp.
 
 rather than the traditional time after the full message is received;
 this will affect the timestamp.
 


@@ -31858,9 +31910,7 @@ If the value of &%av_scanner%& starts with a dollar character, it is expanded
 before use.
 The usual list-parsing of the content (see &<<SECTlistconstruct>>&) applies.
 The following scanner types are supported in this release,
 before use.
 The usual list-parsing of the content (see &<<SECTlistconstruct>>&) applies.
 The following scanner types are supported in this release,

-.new

 though individual ones can be included or not at build time:
 though individual ones can be included or not at build time:

-.wen

 
 .vlist
 .vitem &%avast%&
 
 .vlist
 .vitem &%avast%&


@@ -31874,11 +31924,22 @@ which can be either a full path to a UNIX socket,
 or host and port specifiers separated by white space.
 The host may be a name or an IP address; the port is either a
 single number or a pair of numbers with a dash between.
 or host and port specifiers separated by white space.
 The host may be a name or an IP address; the port is either a
 single number or a pair of numbers with a dash between.

-Any further options are given, on separate lines,
-to the daemon as options before the main scan command.
+A list of options may follow. These options are interpreted on the
+Exim's side of the malware scanner, or are given on separate lines to
+the daemon as options before the main scan command.
+
+.new
+.cindex &`pass_unscanned`& "avast"
+If &`pass_unscanned`&
+is set, any files the Avast scanner can't scan (e.g.
+decompression bombs, or invalid archives) are considered clean. Use with
+care.
+.wen
+

 For example:
 .code
 av_scanner = avast:/var/run/avast/scan.sock:FLAGS -fullfiles:SENSITIVITY -pup
 For example:
 .code
 av_scanner = avast:/var/run/avast/scan.sock:FLAGS -fullfiles:SENSITIVITY -pup

+av_scanner = avast:/var/run/avast/scan.sock:pass_unscanned:FLAGS -fullfiles:SENSITIVITY -pup

 av_scanner = avast:192.168.2.22 5036
 .endd
 If you omit the argument, the default path
 av_scanner = avast:192.168.2.22 5036
 .endd
 If you omit the argument, the default path


@@ -31895,8 +31956,9 @@ $ socat UNIX:/var/run/avast/scan.sock STDIO:
     PACK
 .endd
 
     PACK
 .endd
 

-Only the first virus detected will be reported.
-
+If the scanner returns a temporary failure (e.g. license issues, or
+permission problems), the message is deferred and a paniclog entry is
+written.  The usual &`defer_ok`& option is available.

 
 .vitem &%aveserver%&
 .cindex "virus scanners" "Kaspersky"
 
 .vitem &%aveserver%&
 .cindex "virus scanners" "Kaspersky"


@@ -31947,7 +32009,7 @@ av_scanner = clamd:192.0.2.3 1234 : 192.0.2.4 1234
 If the value of av_scanner points to a UNIX socket file or contains the
 &`local`&
 option, then the ClamAV interface will pass a filename containing the data
 If the value of av_scanner points to a UNIX socket file or contains the
 &`local`&
 option, then the ClamAV interface will pass a filename containing the data

-to be scanned, which will should normally result in less I/O happening and be
+to be scanned, which should normally result in less I/O happening and be

 more efficient.  Normally in the TCP case, the data is streamed to ClamAV as
 Exim does not assume that there is a common filesystem with the remote host.
 
 more efficient.  Normally in the TCP case, the data is streamed to ClamAV as
 Exim does not assume that there is a common filesystem with the remote host.
 


@@ -32029,7 +32091,7 @@ For example:
 .code
 av_scanner = f-protd:localhost 10200-10204
 .endd
 .code
 av_scanner = f-protd:localhost 10200-10204
 .endd

-If you omit the argument, the default values show above are used.
+If you omit the argument, the default values shown above are used.

 
 .vitem &%f-prot6d%&
 .cindex "virus scanners" "f-prot6d"
 
 .vitem &%f-prot6d%&
 .cindex "virus scanners" "f-prot6d"


@@ -36491,6 +36553,7 @@ selection marked by asterisks:
 &` queue_time_overall         `&  time on queue for whole message
 &` pid                        `&  Exim process id
 &` proxy                      `&  proxy address on <= and => lines
 &` queue_time_overall         `&  time on queue for whole message
 &` pid                        `&  Exim process id
 &` proxy                      `&  proxy address on <= and => lines

+&` receive_time               `&  time taken to receive message

 &` received_recipients        `&  recipients on <= lines
 &` received_sender            `&  sender on <= lines
 &`*rejected_header            `&  header contents on reject log
 &` received_recipients        `&  recipients on <= lines
 &` received_sender            `&  sender on <= lines
 &`*rejected_header            `&  header contents on reject log


@@ -39007,8 +39070,16 @@ certtool --load_privkey=dkim_ed25519.private --pubkey_info --outder | tail -c +1
 .wen
 
 .option dkim_hash smtp string&!! sha256
 .wen
 
 .option dkim_hash smtp string&!! sha256

-Can be set alternatively to &"sha1"& to use an alternate hash
-method.
+.new
+Can be set to any one of the supported hash methods, which are:
+.ilist
+&`sha1`& &-- should not be used, is old and insecure
+.next
+&`sha256`& &-- the default
+.next
+&`sha512`& &-- possibly more secure but less well supported
+.endlist
+.wen

 
 .new
 Note that RFC 8301 says:
 
 .new
 Note that RFC 8301 says:


@@ -39336,8 +39407,8 @@ This includes retransmissions done by traditional forwarders.
 SPF verification support is built into Exim if SUPPORT_SPF=yes is set in
 &_Local/Makefile_&.  The support uses the &_libspf2_& library
 &url(http://www.libspf2.org/).
 SPF verification support is built into Exim if SUPPORT_SPF=yes is set in
 &_Local/Makefile_&.  The support uses the &_libspf2_& library
 &url(http://www.libspf2.org/).

-There is no Exim involvement on the trasmission of messages; publishing certain
-DNS records is all that is required.
+There is no Exim involvement in the transmission of messages;
+publishing certain DNS records is all that is required.

 
 For verification, an ACL condition and an expansion lookup are provided.
 .new
 
 For verification, an ACL condition and an expansion lookup are provided.
 .new


@@ -39486,7 +39557,7 @@ address as the key and an IP address as the database:
   ${lookup {username@domain} spf {ip.ip.ip.ip}}
 .endd
 
   ${lookup {username@domain} spf {ip.ip.ip.ip}}
 .endd
 

-The lookup will return the same result strings as they can appear in
+The lookup will return the same result strings as can appear in

 &$spf_result$& (pass,fail,softfail,neutral,none,err_perm,err_temp).
 Currently, only IPv4 addresses are supported.
 
 &$spf_result$& (pass,fail,softfail,neutral,none,err_perm,err_temp).
 Currently, only IPv4 addresses are supported.