X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/71bb51e08dc03f768d19f237fed415bc74246de3..46d2a5e6f6e7709d172903b13945d23fc0a2c888:/doc/doc-txt/ChangeLog

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 786df0506..be07ba625 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -1,19 +1,583 @@
-Change log file for Exim from version 4.21
-------------------------------------------
 This document describes *changes* to previous versions, that might
 affect Exim's operation, with an unchanged configuration file.  For new
 options, and new features, see the NewStuff file next to this ChangeLog.
 
 
-Since Exim version 4.90
------------------------
+Exim version 4.94
+-----------------
+
+JH/01 Avoid costly startup code when not strictly needed.  This reduces time
+      for some exim process initialisations.  It does mean that the logging
+      of TLS configuration problems is only done for the daemon startup.
+
+JH/02 Early-pipelining support code is now included unless disabled in Makefile.
+
+JH/03 DKIM verification defaults no long accept sha1 hashes, to conform to
+      RFC 8301.  They can still be enabled, using the dkim_verify_hashes main
+      option.
+
+JH/04 Support CHUNKING from an smtp transport using a transport_filter, when
+      DKIM signing is being done.  Previously a transport_filter would always
+      disable CHUNKING, falling back to traditional DATA.
+
+JH/05 Regard command-line receipients as tainted.
+
+JH/06 Bug 340: Remove the daemon pid file on exit, whe due to SIGTERM.
+
+JH/07 Bug 2489: Fix crash in the "pam" expansion condition.  It seems that the
+      PAM library frees one of the arguments given to it, despite the
+      documentation.  Therefore a plain malloc must be used.
+
+JH/08 Bug 2491: Use tainted buffers for the transport smtp context.  Previously
+      on-stack buffers were used, resulting in a taint trap when DSN information
+      copied from a received message was written into the buffer.
+
+JH/09 Bug 2493: Harden ARC verify against Outlook, whick has been seen to mix
+      the ordering of its ARC headers.  This caused a crash.
+
+JH/10 Bug 2492: Use tainted memory for retry record when needed.  Previously when
+      a new record was being constructed with information from the peer, a trap
+      was taken.
+
+JH/11 Bug 2494: Unset the default for dmarc_tld_file.  Previously a naiive
+      installation would get error messages from DMARC verify, when it hit the
+      nonexistent file indicated by the default.  Distros wanting DMARC enabled
+      should both provide the file and set the option.
+      Also enforce no DMARC verification for command-line sourced messages.
+
+JH/12 Fix an uninitialised flag in early-pipelining.  Previously connections
+      could, depending on the platform, hang at the STARTTLS response.
+
+JH/13 Bug 2498: Reset a counter used for ARC verify before handling another
+      message on a connection.  Previously if one message had ARC headers and
+      the following one did not, a crash could result when adding an
+      Authentication-Results: header.
+
+JH/14 Bug 2500: Rewind some of the common-coding in string handling between the
+      Exim main code and Exim-related utities.  The introduction of taint
+      tracking also did many adjustments to string handling.  Since then, eximon
+      frequently terminated with an assert failure.
+
+JH/15 When PIPELINING, synch after every hundred or so RCPT commands sent and
+      check for 452 responses.  This slightly helps the inefficieny of doing
+      a large alias-expansion into a recipient-limited target.  The max_rcpt
+      transport option still applies (and at the current default, will override
+      the new feature).  The check is done for either cause of synch, and forces
+      a fast-retry of all 452'd recipients using a new MAIL FROM on the same
+      connection.  The new facility is not tunable at this time.
+
+JH/16 Fix the variables set by the gsasl authenticator.  Previously a pointer to
+      library live data was being used, so the results became garbage.  Make
+      copies while it is still usable.
+
+JH/17 Logging: when the deliver_time selector ise set, include the DT= field
+      on delivery deferred (==) and failed (**) lines (if a delivery was
+      attemtped).  Previously it was only on completion (=>) lines.
+
+JH/18 Authentication: the gsasl driver not provides the $authN variables in time
+      for the expansion of the server_scram_iter and server_scram_salt options.
+
+WB/01 SPF: DNS lookups for the obsolete SPF RR type done by the libspf2 library
+      are now specifically given a NO_DATA response without hitting the system
+      resolver.  The library goes on to do the now-standard TXT lookup.
+      Use of dnsdb lookups is not affected.
+
+JH/19 Bug 2507: Modules: on handling a dynamic-module (lookups) open failure,
+      only retrieve the errormessage once.  Previously two calls to dlerror()
+      were used, and the second one (for mainlog/paniclog) retrieved null
+      information.
+
+JH/20 Taint checking: disallow use of tainted data for
+      - the appendfile transport file and directory options
+      - the pipe transport command
+      - the autoreply transport file, log and once options
+      - file names used by the redirect router (including filter files)
+      - named-queue names
+      Previously this was permitted.
+
+JH/21 Bug 2501: Fix init call in the heimdal authenticator.  Previously it
+      adjusted the size of a major service buffer; this failed because the
+      buffer was in use at the time.  Change to a compile-time increase in the
+      buffer size, when this authenticator is compiled into exim.
+
+JH/22 Taint-checking: move to safe-mode taint checking on all platforms.  The
+      previous fast-mode was untenable in the face of glibs using mmap to
+      support larger malloc requests.
+
+PP/01 Update the openssl_options possible values through OpenSSL 1.1.1c.
+      New values supported, if defined on system where compiled:
+      allow_no_dhe_kex, cryptopro_tlsext_bug, enable_middlebox_compat,
+      no_anti_replay, no_encrypt_then_mac, prioritize_chacha, tlsext_padding
+
+JH/23 Performance improvement in the initial phase of a two-pass queue run.  By
+      running a limited number of proceses in parallel, a benefit is gained. The
+      amount varies with the platform hardware and load.  The use of the option
+      queue_run_in_order means we cannot do this, as ordering becomes
+      indeterminate.
+
+JH/24 Bug 2524: fix the cyrus_sasl auth driver gssapi usage.  A previous fix
+      had introduced a string-copy (for ensuring NUL-termination) which was not
+      appropriate for that case, which can include embedded NUL bytes in the
+      block of data.  Investigation showed the copy to actually be needless, the
+      data being length-specified.
+
+JH/25 Fix use of concurrent TLS connections under GnuTLS.  When a callout was
+      done during a receiving connection, and both used TLS, global info was
+      used rather than per-connection info for tracking the state of data
+      queued for transmission.  This could result in a connection hang.
+
+JH/26 Fix use of the SIZE parameter on MAIL commands, on continued connections.
+      Previously, when delivering serveral messages down a single connection
+      only the first would provide a SIZE.  This was due to the size information
+      not being properly tracked.
+
+JH/27 Bug 2530: When operating in a timezone with sub-minute offset, such as
+      TAI (at 37 seconds currently), pretend to be in UTC for time-related
+      expansion and logging.  Previously, spurious values such as a future
+      minute could be seen.
+
+JH/28 Bug 2533: Fix expansion of ${tr } item.  When called in some situations
+      it could crash from a null-deref.  This could also affect the
+      ${addresses: } operator and ${readsock } item.
+
+JH/29 Bug 2537: Fix $mime_part_count.  When a single connection had a non-mime
+      message following a mime one, the variable was not reset.
+
+JH/30 When an pipelined-connect fails at the first response, assume incorrect
+      cached capability (perhaps the peer reneged?) and immediately retry in
+      non-pipelined mode.
+
+JH/31 Fix spurious detection of timeout while writing to transport filter.
+
+JH/32 Bug 2541: Fix segfault on bad cmdline -f (sender) argument.  Previously
+      an attempt to copy the string was made before checking it.
+
+JH/33 Fix the dsearch lookup to return an untainted result.  Previously the
+      taint of the lookup key was maintained; we now regard the presence in the
+      filesystem as sufficient validation.
+
+
+Exim version 4.93
+-----------------
+
+JH/01 OpenSSL: With debug enabled output keying information sufficient, server
+      side, to decode a TLS 1.3 packet capture.
+
+JH/02 OpenSSL: Suppress the sending of (stateful) TLS1.3 session tickets.
+      Previously the default library behaviour applied, sending two, each in
+      its own TCP segment.
+
+JH/03 Debug output for ACL now gives the config file name and line number for
+      each verb.
+
+JH/04 The default received_header_text now uses the RFC 8314 tls cipher clause.
+
+JH/05 DKIM: ensure that dkim_domain elements are lowercased before use.
+
+JH/06 Fix buggy handling of autoreply bounce_return_size_limit, and a possible
+      buffer overrun for (non-chunking) other transports.
+
+JH/07 GnuTLS: Our use of late (post-handshake) certificate verification, under
+      TLS1.3, means that a server rejecting a client certificate is not visible
+      to the client until the first read of encrypted data (typically the
+      response to EHLO).  Add detection for that case and treat it as a failed
+      TLS connection attempt, so that the normal retry-in-clear can work (if
+      suitably configured).
+
+JB/01 Bug 2375: fix expansions of 822 addresses having comments in local-part
+      and/or domain.  Found and fixed by Jason Betts.
+
+JH/08 Add hardening against SRV & TLSA lookups the hit CNAMEs (a nonvalid
+      configuration).  If a CNAME target was not a wellformed name pattern, a
+      crash could result.
+
+JH/09 Logging: Fix initial listening-on line for multiple ports for an IP when
+      the OS reports them interleaved with other addresses.
+
+JH/10 OpenSSL: Fix aggregation of messages.  Previously, when PIPELINING was
+      used both for input and for a verify callout, both encrypted, SMTP
+      responses being sent by the server could be lost.  This resulted in
+      dropped connections and sometimes bounces generated by a peer sending
+      to this system.
+
+JH/11 Harden plaintext authenticator against a badly misconfigured client-send
+      string.  Previously it was possible to cause undefined behaviour in a
+      library routine (usually a crash).  Found by "zerons".
+
+JH/12 Bug 2384: fix "-bP smtp_receive_timeout".  Previously it returned no
+      output.
+
+JH/13 Bug 2386: Fix builds with Dane under LibreSSL 2.9.0 onward.  Some old
+      API was removed, so update to use the newer ones.
+
+JH/14 Bug 1891: Close the log file if receiving a non-smtp message, without
+      any timeout set, is taking a long time.  Previously we would hang on to a
+      rotated logfile "forever" if the input was arriving with long gaps
+      (a previous attempt to fix addressed lack, for a long time, of initial
+      input).
+
+HS/01 Bug 2390: Use message_id for tempfile creation to avoid races in a
+      shared (NFS) environment. The length of the tempfile name is now
+      4 + 16 ("hdr.$message_exim_id") which might break on file
+      systems which restrict the file name length to lower values.
+      (It was "hdr.$pid".)
+
+HS/02 Bug 2390: Use message_id for tempfile creation to avoid races in a
+      shared (NFS) environment.
+
+HS/03 Bug 2392: exigrep does case sensitive *option* processing (as it
+      did for all versions <4.90). Notably -M, -m, --invert, -I may be
+      affected.
+
+JH/15 Use unsigned when creating bitmasks in macros, to avoid build errors
+      on some platforms for bit 31.
+
+JH/16 GnuTLS: rework ciphersuite strings under recent library versions.  Thanks
+      to changes apparently associated with TLS1.3 handling some of the APIs
+      previously used were either nonfunctional or inappropriate.  Strings
+      like TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM__AEAD:256
+      and TLS1.2:ECDHE_SECP256R1__RSA_SHA256__AES_128_CBC__SHA256:128 replace
+      the previous TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256 .
+      This affects log line X= elements, the $tls_{in,out}_cipher variables,
+      and the use of specific cipher names in the encrypted= ACL condition.
+
+JH/17 OpenSSL: the default openssl_options now disables ssl_v3.
+
+JH/18 GnuTLS: fix $tls_out_ocsp under hosts_request_ocsp. Previously the
+      verification result was not updated unless hosts_require_ocsp applied.
+
+JH/19 Bug 2398: fix listing of a named-queue.  Previously, even with the option
+      queue_list_requires_admin set to false, non-admin users were denied the
+      facility.
+
+JH/20 Bug 2389: fix server advertising of usable certificates, under GnuTLS in
+      directory-of-certs mode.  Previously they were advertised despite the
+      documentation.
+
+JH/21 The smtp transport option "hosts_noproxy_tls" is now unset by default.
+      A single TCP connection by a client will now hold a TLS connection open
+      for multiple message deliveries, by default.  Previoud the default was to
+      not do so.
+
+JH/22 The smtp transport option "hosts_try_dane" now enables all hosts by
+      default.  If built with the facility, DANE will be used.  The facility
+      SUPPORT_DANE is now enabled in the prototype build Makefile "EDITME".
+
+JH/23 The build default is now for TLS to be included; the SUPPORT_TLS define
+      is replaced with DISABLE_TLS.  Either USE_GNUTLS or (the new) USE_OPENSSL
+      must be defined and you must still, unless you define DISABLE_TLS, manage
+      the the include-dir and library-file requirements that go with that
+      choice.  Non-TLS builds are still supported.
+
+JH/24 Fix duplicated logging of peer name/address, on a transport connection-
+      reject under TFO.
+
+JH/25 The smtp transport option "hosts_try_fastopen" now enables all hosts by
+      default.  If the platform supports and has the facility enabled, it will
+      be requested on all coneections.
+
+JH/26 The PIPE_CONNECT facility is promoted from experimental status and is now
+      controlled by the build-time option SUPPORT_PIPE_CONNECT.
+
+PP/01 Unbreak heimdal_gssapi, broken in 4.92.
+
+JH/27 Bug 2404: Use the main-section configuration option "dsn_from" for
+      success-DSN messages.  Previously the From: header was always the default
+      one for these; the option was ignored.
+
+JH/28 Fix the timeout on smtp response to apply to the whole response.
+      Previously it was reset for every read, so a teergrubing peer sending
+      single bytes within the time limit could extend the connection for a
+      long time.  Credit to Qualsys Security Advisory Team for the discovery.
+
+JH/29 Fix DSN Final-Recipient: field.  Previously it was the post-routing
+      delivery address, which leaked information of the results of local
+      forwarding.  Change to the original envelope recipient address, per
+      standards.
+
+JH/30 Bug 2411: Fix DSN generation when RFC 3461 failure notification is
+      requested.  Previously not bounce was generated and a log entry of
+      error ignored was made.
+
+JH/31 Avoid re-expansion in ${sort } expansion. (CVE-2019-13917)
+
+JH/32 Introduce a general tainting mechanism for values read from the input
+      channel, and values derived from them.  Refuse to expand any tainted
+      values, to catch one form of exploit.
+
+JH/33 Bug 2413: Fix dkim_strict option.  Previously the expansion result
+      was unused and the unexpanded text used for the test.  Found and
+      fixed by Ruben Jenster.
+
+JH/34 Fix crash after TLS shutdown.  When the TCP/SMTP channel was left open,
+      an attempt to use a TLS library read routine dereffed a nul pointer,
+      causing a segfault.
+
+JH/35 Bug 2409: filter out-of-spec chars from callout response before using
+      them in our smtp response.
+
+JH/36 Have the general router option retry_use_local_part default to true when
+      any of the restrictive preconditions are set (to anything).  Previously it
+      was only for check_local user.  The change removes one item of manual
+      configuration which is required for proper retries when a remote router
+      handles a subset of addresses for a domain.
+
+JH/37 Appendfile: when evaluating quota use (non-quota_size_regex) take the file
+      link count into consideration.
+
+HS/04 Fix handling of very log lines in -H files. If a -<key> <value> line
+      caused the extension of big_buffer, the following lines were ignored.
+
+JH/38 Bug 1395: Teach the DNS negative-cache about TTL value from the SOA in
+      accordance with RFC 2308.  Previously there was no expiry, so a longlived
+      receive process (eg. due to ACL delays) versus a short SOA value could
+      surprise.
+
+HS/05 Handle trailing backslash gracefully. (CVE-2019-15846)
+
+JH/39 Promote DMARC support to mainline.
+
+JH/40 Bug 2452: Add a References: header to DSNs.
+
+JH/41 With GnuTLS 3.6.0 (and later) do not attempt to manage Diffie-Hellman
+      parameters.  The relevant library call is documented as "Deprecated: This
+      function is unnecessary and discouraged on GnuTLS 3.6.0 or later. Since
+      3.6.0, DH parameters are negotiated following RFC7919."
+
+HS/06 Change the default of dnssec_request_domains to "*"
+
+JH/42 Bug 2545: Fix CHUNKING for all RCPT commands rejected.  Previously we
+      carried on and emitted a BDAT command, even when PIPELINING was not
+      active.
+
+JH/43 Bug 2465: Fix taint-handling in dsearch lookup.  Previously a nontainted
+      buffer was used for the filename, resulting in a trap when tainted
+      arguments (eg. $domain) were used.
+
+JH/44 With OpenSSL 1.1.1 (onwards) disable renegotiation for TLS1.2 and below;
+      recommended to avoid a possible server-load attack.  The feature can be
+      re-enabled via the openssl_options main cofiguration option.
+
+JH/45 local_scan API: documented the current smtp_printf() call. This changed
+      for version 4.90 - adding a "more data" boolean to the arguments.
+      Bumped the ABI version number also, this having been missed previously;
+      release versions 4.90 to 4.92.3 inclusive were effectively broken in
+      respect of usage of smtp_printf() by either local_scan code or libraries
+      accessed via the ${dlfunc } expansion item.  Both will need coding
+      adjustment for any calls to smtp_printf() to match the new function
+      signature; a FALSE value for the new argument is always safe.
+
+JH/46 FreeBSD: fix use of the sendfile() syscall.  The shim was not updating
+      the file-offset (which the Linux syscall does, and exim expects); this
+      resulted in an indefinite loop.
+
+JH/47 ARC: fix crash in signing, triggered when a configuration error failed
+      to do ARC verification.  The Authentication-Results: header line added
+      by the configuration then had no ARC item.
+
+
+Exim version 4.92
+-----------------
+
+JH/01 Remove code calling the customisable local_scan function, unless a new
+      definition "HAVE_LOCAL_SCAN=yes" is present in the Local/Makefile.
+
+JH/02 Bug 1007: Avoid doing logging from signal-handlers, as that can result in
+      non-signal-safe functions being used.
+
+JH/03 Bug 2269: When presented with a received message having a stupidly large
+      number of DKIM-Signature headers, disable DKIM verification to avoid
+      a resource-consumption attack.  The limit is set at twenty.
+
+JH/04 Add variables $arc_domains, $arc_oldest_pass for ARC verify.  Fix the
+      report of oldest_pass in ${authres } in consequence, and separate out
+      some descriptions of reasons for verification fail.
+
+JH/05 Bug 2273: Cutthrough delivery left a window where the received messsage
+      files in the spool were present and unlocked.  A queue-runner could spot
+      them, resulting in a duplicate delivery.  Fix that by doing the unlock
+      after the unlink.  Investigation by Tim Stewart.  Take the opportunity to
+      add more error-checking on spoolfile handling while that code is being
+      messed with.
+
+PP/01 Refuse to open a spool data file (*-D) if it's a symlink.
+      No known attacks, no CVE, this is defensive hardening.
+
+JH/06 Bug 2275: The MIME ACL unlocked the received message files early, and
+      a queue-runner could start a delivery while other operations were ongoing.
+      Cutthrough delivery was a common victim, resulting in duplicate delivery.
+      Found and investigated by Tim Stewart.  Fix by using the open message data
+      file handle rather than opening another, and not locally closing it (which
+      releases a lock) for that case, while creating the temporary .eml format
+      file for the MIME ACL.  Also applies to "regex" and "spam" ACL conditions.
+
+JH/07 Bug 177: Make a random-recipient callout success visible in ACL, by setting
+      $sender_verify_failure/$recipient_verify_failure to "random".
+
+JH/08 When generating a selfsigned cert, use serial number 1 since zero is not
+      legitimate.
+
+JH/09 Bug 2274: Fix logging of cmdline args when starting in an unlinked cwd.
+      Previously this would segfault.
+
+JH/10 Fix ARC signing for case when DKIM signing failed.  Previously this would
+      segfault.
+
+JH/11 Bug 2264: Exim now only follows CNAME chains one step by default. We'd
+      like zero, since the resolver should be doing this for us, But we need one
+      as a CNAME but no MX presence gets the CNAME returned; we need to check
+      that doesn't point to an MX to declare it "no MX returned" rather than
+      "error, loop".  A new main option is added so the older capability of
+      following some limited number of chain links is maintained.
+
+JH/12 Add client-ip info to non-pass iprev ${authres } lines.
+
+JH/13 For receent Openssl versions (1.1 onward) use modern generic protocol
+      methods.  These should support TLS 1.3; they arrived with TLS 1.3 and the
+      now-deprecated earlier definitions used only specified the range up to TLS
+      1.2 (in the older-version library docs).
+
+JH/14 Bug 2284: Fix DKIM signing for body lines starting with a pair of dots.
+
+JH/15 Rework TLS client-side context management.  Stop using a global, and
+      explicitly pass a context around.  This enables future use of TLS for
+      connections to service-daemons (eg. malware scanning) while a client smtp
+      connection is using TLS; with cutthrough connections this is quite likely.
+
+JH/16 Fix ARC verification to do AS checks in reverse order.
+
+JH/17 Support a "tls" option on the ${readsocket } expansion item.
+
+JH/18 Bug 2287: Fix the protocol name (eg utf8esmtp) for multiple messages
+      using the SMTPUTF8 option on their MAIL FROM commands, in one connection.
+      Previously the "utf8" would be re-prepended for every additional message.
+
+JH/19 Reject MAIL FROM commands with SMTPUTF8 when the facility was not advertised.
+      Previously thery were accepted, resulting in issues when attempting to
+      forward messages to a non-supporting MTA.
+
+PP/02 Let -n work with printing macros too, not just options.
+
+JH/20 Bug 2296: Fix cutthrough for >1 address redirection.  Previously only
+      one parent address was copied, and bogus data was used at delivery-logging
+      time.  Either a crash (after delivery) or bogus log data could result.
+      Discovery and analysis by Tim Stewart.
+
+PP/03 Make ${utf8clean:} expansion operator detect incomplete final character.
+      Previously if the string ended mid-character, we did not insert the
+      promised '?' replacement.
+
+PP/04 Documentation: current string operators work on bytes, not codepoints.
+
+JH/21 Change as many as possible of the global flags into one-bit bitfields; these
+      should pack well giving a smaller memory footprint so better caching and
+      therefore performance.  Group the declarations where this can't be done so
+      that the byte-sized flag variables are not interspersed among pointer
+      variables, giving a better chance of good packing by the compiler.
+
+JH/22 Bug 1896: Fix the envelope from for DMARC forensic reports to be possibly
+      non-null, to avoid issues with sites running BATV.  Previously reports were
+      sent with an empty envelope sender so looked like bounces.
+
+JH/23 Bug 2318: Fix the noerror command within filters.  It wasn't working.
+      The ignore_error flag wasn't being returned from the filter subprocess so
+      was not set for later routers.  Investigation and fix by Matthias Kurz.
+
+JH/24 Bug 2310: Raise a msg:fail:internal event for each undelivered recipient,
+      and a msg:complete for the whole, when a message is manually removed using
+      -Mrm.  Developement by Matthias Kurz, hacked on by JH.
+
+JH/25 Avoid fixed-size buffers for pathnames in DB access.  This required using
+      a "Gnu special" function, asprintf() in the DB utility binary builds; I
+      hope that is portable enough.
+
+JH/26 Bug 2311: Fix DANE-TA verification under GnuTLS.  Previously it was also
+      requiring a known-CA anchor certificate; make it now rely entirely on the
+      TLSA as an anchor.  Checking the name on the leaf cert against the name
+      on the A-record for the host is still done for TA (but not for EE mode).
+
+JH/27 Fix logging of proxy address.  Previously, a pointless "PRX=[]:0" would be
+      included in delivery lines for non-proxied connections, when compiled with
+      SUPPORT_SOCKS and running with proxy logging enabled.
+
+JH/28 Bug 2314: Fire msg:fail:delivery event even when error is being ignored.
+      Developement by Matthias Kurz, tweaked by JH.  While in that bit of code,
+      move the existing event to fire before the normal logging of message
+      failure so that custom logging is bracketed by normal logging.
+
+JH/29 Bug 2322: A "fail" command in a non-system filter (file) now fires the
+      msg:fail:internal event.  Developement by Matthias Kurz.
+
+JH/30 Bug 2329: Increase buffer size used for dns lookup from 2k, which was
+      far too small for todays use of crypto signatures stored there.  Go all
+      the way to the max DNS message size of 64kB, even though this might be
+      overmuch for IOT constrained device use.
+
+JH/31 Fix a bad use of a copy function, which could be used to pointlessly
+      copy a string over itself.  The library routine is documented as not
+      supporting overlapping copies, and on MacOS it actually raised a SIGABRT.
+
+JH/32 For main options check_spool_space and check_inode_space, where the
+      platform supports 64b integers, support more than the previous 2^31 kB
+      (i.e. more than 2 TB).  Accept E, P and T multipliers in addition to
+      the previous G, M, k.
+
+JH/33 Bug 2338: Fix the cyrus-sasl authenticator to fill in the
+      $authenticated_fail_id variable on authentication failure.  Previously
+      it was unset.
+
+JH/34 Increase RSA keysize of autogen selfsign cert from 1024 to 2048.  RHEL 8.0
+      OpenSSL didn't want to use such a weak key.  Do for GnuTLS also, and for
+      more-modern GnuTLS move from GNUTLS_SEC_PARAM_LOW to
+      GNUTLS_SEC_PARAM_MEDIUM.
+
+JH/35 OpenSSL: fail the handshake when SNI processing hits a problem, server
+      side.  Previously we would continue as if no SNI had been received.
+
+JH/36 Harden the handling of string-lists.  When a list consisted of a sole
+      "<" character, which should be a list-separator specification, we walked
+      off past the nul-terimation.
+
+JH/37 Bug 2341: Send "message delayed" warning MDNs (restricted to external
+      causes) even when the retry time is not yet met.  Previously they were
+      not, meaning that when (say) an account was over-quota and temp-rejecting,
+      and multiple senders' messages were queued, only one sender would get
+      notified on each configured delay_warning cycle.
+
+JH/38 Bug 2351: Log failures to extract envelope addresses from message headers.
+
+JH/39 OpenSSL: clear the error stack after an SSL_accept().  With anon-auth
+      cipher-suites, an error can be left on the stack even for a succeeding
+      accept; this results in impossible error messages when a later operation
+      actually does fail.
+
+AM/01 Bug 2359: GnuTLS: repeat lowlevel read and write operations while they
+      return error codes indicating retry.  Under TLS1.3 this becomes required.
+
+JH/40 Fix the feature-cache refresh for EXPERIMENTAL_PIPE_CONNECT.  Previously
+      it only wrote the new authenticators, resulting in a lack of tracking of
+      peer changes of ESMTP extensions until the next cache flush.
+
+JH/41 Fix the loop reading a message header line to check for integer overflow,
+      and more-often against header_maxsize.  Previously a crafted message could
+      induce a crash of the recive process; now the message is cleanly rejected.
+
+JH/42 Bug 2366: Fix the behaviour of the dkim_verify_signers option.  It had
+      been totally disabled for all of 4.91.  Discovery and fix by "Mad Alex".
+
+
+Exim version 4.91
+-----------------
 
 GF/01 DEFER rather than ERROR on redis cluster MOVED response.
-     When redis_servers is set to a list of > 1 element, and the Redis servers
-     in that list are in cluster configuration, convert the REDIS_REPLY_ERROR
-     case of MOVED into a DEFER case instead, thus moving the query onto the
-     next server in the list. For a cluster of N elements, all N servers must
-     be defined in redis_servers.
+      When redis_servers is set to a list of > 1 element, and the Redis servers
+      in that list are in cluster configuration, convert the REDIS_REPLY_ERROR
+      case of MOVED into a DEFER case instead, thus moving the query onto the
+      next server in the list. For a cluster of N elements, all N servers must
+      be defined in redis_servers.
+
+GF/02 Catch and remove uninitialized value warning in exiqsumm
+      Check for existence of @ARGV before looking at $ARGV[0]
 
 JH/01 Replace the store_release() internal interface with store_newblock(),
       which internalises the check required to safely use the old one, plus
@@ -141,6 +705,77 @@ JH/27 Bug 2251: Fix ldap lookups that return a single attribute having zero-
 HS/02 Support Avast multiline protoocol, this allows passing flags to
       newer versions of the scanner.
 
+JH/28 Ensure that variables possibly set during message acceptance are marked
+      dead before release of memory in the daemon loop.  This stops complaints
+      about them when the debug_store option is enabled.  Discovered specifically
+      for sender_rate_period, but applies to a whole set of variables.
+      Do the same for the queue-runner and queue-list loops, for variables set
+      from spool message files.  Do the same for the SMTP per-message loop, for
+      certain variables indirectly set in ACL operations.
+
+JH/29 Bug 2250: Fix a longstanding bug in heavily-pipelined SMTP input (such
+      as a multi-recipient message from a mailinglist manager).  The coding had
+      an arbitrary cutoff number of characters while checking for more input;
+      enforced by writing a NUL into the buffer.  This corrupted long / fast
+      input.   The problem was exposed more widely when more pipelineing of SMTP
+      responses was introduced, and one Exim system was feeding another.
+      The symptom is log complaints of SMTP syntax error (NUL chars) on the
+      receiving system, and refused recipients seen by the sending system
+      (propating to people being dropped from mailing lists).
+      Discovered and pinpointed by David Carter.
+
+JH/30 The (EXPERIMENTAL_DMARC) variable $dmarc_ar_header is withdrawn, being
+      replaced by the ${authresults } expansion.
+
+JH/31 Bug 2257: Fix pipe transport to not use a socket-only syscall.
+
+HS/03 Set a handler for SIGTERM and call exit(3) if running as PID 1. This
+      allows proper process termination in container environments.
+
+JH/32 Bug 2258: Fix spool_wireformat in combination with LMTP transport.
+      Previously the "final dot" had a newline after it; ensure it is CR,LF.
+
+JH/33 SPF: remove support for the "spf" ACL condition outcome values "err_temp"
+      and "err_perm", deprecated since 4.83 when the RFC-defined words
+      "temperror" and "permerror" were introduced.
+
+JH/34 Re-introduce enforcement of no cutthrough delivery on transports having
+      transport-filters or DKIM-signing.  The restriction was lost in the
+      consolidation of verify-callout and delivery SMTP handling.
+      Extend the restriction to also cover ARC-signing.
+
+JH/35 Cutthrough: for a final-dot response timeout (and nonunderstood responses)
+      in defer=pass mode supply a 450 to the initiator.  Previously the message
+      would be spooled.
+
+PP/02 DANE: add dane_require_tls_ciphers SMTP Transport option; if unset,
+      tls_require_ciphers is used as before.
+
+HS/03 Malware Avast: Better match the Avast multiline protocol. Add
+      "pass_unscanned".  Only tmpfails from the scanner are written to
+      the paniclog, as they may require admin intervention (permission
+      denied, license issues). Other scanner errors (like decompression
+      bombs) do not cause a paniclog entry.
+
+JH/36 Fix reinitialisation of DKIM logging variable between messages.
+      Previously it was possible to log spurious information in receive log
+      lines.
+
+JH/37 Bug 2255: Revert the disable of the OpenSSL session caching.  This
+      triggered odd behaviour from Outlook Express clients.
+
+PP/03 Add util/renew-opendmarc-tlds.sh script for safe renewal of public
+      suffix list.
+
+JH/38 DKIM: accept Ed25519 pubkeys in SubjectPublicKeyInfo-wrapped form,
+      since the IETF WG has not yet settled on that versus the original
+      "bare" representation.
+
+JH/39 Fix syslog logging for syslog_timestamp=no and log_selector +millisec.
+      Previously the millisecond value corrupted the output.
+      Fix also for syslog_pid=no and log_selector +pid, for which the pid
+      corrupted the output.
+
 
 Exim version 4.90
 -----------------
@@ -297,7 +932,7 @@ JH/26 Fix DKIM bug: when the pseudoheader generated for signing was exactly
       line, the header hash was calculated to an incorrect value thanks to
       the (relaxed) space the fold became.
 
-HS/02 Fix Bug 2130: large writes from the transport subprocess where chunked
+HS/02 Fix Bug 2130: large writes from the transport subprocess were chunked
       and confused the parent.
 
 JH/27 Fix SOCKS bug: an unitialized pointer was deref'd by the transport process