Exim 4.99-RC3 is now available for testing and feedback, marking the third stage in the development process leading to Exim 4.99's official release. This release candidate includes several bug fixes and new features, such as sieve inbox options, a "connection_id" variable, and improved support for IPv6 addresses in MySQL and PgSQL lookups. The build process has also been streamlined with optional experimental features like SPF_PERL and NMH, as well as support for SRV records specifying TLS availability.

Exim 4.99 Release Candidate 3 released

A new release candidate, v4.99-RC3, is now available for testing and feedback. This milestone marks the third stage in the development process leading to Exim 4.99's official release.

With the source base now closed for feature additions, this release candidate is a critical step in identifying and resolving any remaining issues. We kindly request that you thoroughly test RC3 to provide valuable feedback before Exim 4.99's official release.

The changes since 4.99-RC2 are primarily focused on bug fixes. A notable improvement includes the addition of H= and U= tags to "authenticator failed" log lines, which not only aligns with standard logging conventions but also makes the remote IP address available for eximstats processing.

New features in this release include several significant additions:

Exim now supports sieve inbox options for redirect routers, making it easier to manage complex routing scenarios. Additionally, the introduction of a "connection_id" variable enables better tracking and debugging of email connections.

Moreover, Exim 4.99-RC3 introduces events for SMTP protocol failures due to syntax or communication issues (smtp:fail:syntax and smtp:fail:protocol). This enhancement will facilitate more precise logging and analysis in various scenarios.

The build process has also been streamlined with several improvements:

1. The inclusion of JSON and LDAP lookup support, as well as filter types, PAM, RADIUS, perl, SPF, DKIM, DMARC, and ARC, can now be omitted at build time to reduce the size of the compiled binary.
2. A transport "socks_proxy" may expand to an empty string, indicating that no proxying should take place.
3. New variables, dmarc_alignment_spf and dmarc_alignment_dkim, have been introduced to handle DMARC-related issues.
4. ATRN support has been added, enabling both providers and customers to utilize this feature.

Other enhancements include

1. Improved IPv6 address support for mysql and pgsql lookups
2. Cut-through deliveries can now use an envelope-from specified by a transport
3. Options in manual-route routers and smtp transports are expanded
4. Fallback hosts in smtp transports and all routers are now expanded
5. Support has been added for SRV records specifying TLS availability, following the IETF draft ()
6. A "log_ports" option in the main section allows filtering of logged port numbers
7. Additional delivery log line elements have been added for protocol details
8. A command-line option is available for pre-config debug
9. Experimental features, including SPF_PERL and NMH, are now optional during the build process

Security has also received attention in this release candidate:

1. Fixes for CVE-2025-26794 and CVE-2025-30232 have been included.
2. Notable bug fixes address issues with hintsdb support when compiled using sqlite3, coding errors in the SPA authenticator, verification of interfaces on continued-connection transports, and problems with parsing DKIM pubkey DNS records.

A crash fix has also been applied to the DKIM signing process.

Overall, this release candidate represents a major phase in Exim 4.99's development, with numerous bug fixes and new features aimed at enhancing its functionality and security.

You can download RC3 as a tarball from here or by directly cloning the Git repository at https://code.exim.org/exim/exim with the tag exim-4.99-RC3.