The first release candidate for the Exim 4.99 Mail Transport Agent has been released for testing, marking a new milestone towards a major update with numerous improvements and fixes since Exim 4.98. The release candidate is available for testing as a tarball or directly from Git. Notable features and enhancements include support for JSON, LDAP lookup, loadable modules, and improved security fixes for CVE-2025-26794 and CVE-2025-30232. 

Exim 4.99-RC1 available for testing

A new release candidate, Exim 4.99-RC1, has been released, marking the beginning of the next journey towards a new version with numerous improvements and fixes since 4.98.

Availability of the Release Candidate

The Exim 4.99-RC1 release candidate is now available for testing:

• As a tarball from: https://ftp.exim.org/pub/exim/exim4/test 
• Directly from Git: https://code.exim.org/exim/exim (tag: exim-4.99-RC1)

Verification of the Release Candidate

To ensure the integrity of the release candidate, please verify its authenticity by checking the signatures using the following key: Key ID: 0xBCE58C8CE41F32DF Email:

What's New in Exim 4.99-RC1?

Numerous features and enhancements have been added since Exim 4.98, including:

1. Sieve Inbox Option: A new option for redirect routers to use sieve_inbox.
2. Connection ID Variable: A variable has been introduced to track connection IDs.
3. SMTP Fail Events: Two new events have been added: smtp:fail:protocol and smtp:fail:syntax.
4. Exim- and Sieve Filter Options: Support for Exim- and Sieve filters can be omitted at build time.
5. Lookup Support: JSON, LDAP lookup support has been added, along with filter types, PAM, RADIUS, perl, SPF, DKIM, DMARC, and ARC support.
6. Loadable Modules: Router and authenticator drivers, as well as transport drivers (except smtp), can now be built as loadable modules.
7. Empty Proxy String: The socks_proxy transport option may expand to an empty string, specifying no proxying.
8. DMARC Alignment Variables: Two new variables have been introduced: dmarcalignmentspfanddmarca​lignments​pfanddmarc_alignment_dkim.
9. ATRN Support: Both provider and customer ATRN support has been added.
10. IPv6 Address Support: IPv6 address support has been added for mysql and pgsql lookups.
11. CCutthrough Deliveries: Cutthrough deliveries can now use an envelope-from address specified by a transport.
12. Host Randomization: The hosts_randomize option in manualroute router and smtp transport is now expanded.
13. Fallback Hosts: The fallback_hosts option in smtp transport and all routers is now expanded.
14. TLS SRV Records: Support for SRV records specifying TLS availability has been added ().
15. Log Ports Filtering: A new main-section option "log_ports" allows filtering logged port numbers.
16. Delivery Log Line Element: Additional delivery log line element, under the "protocol detail" control, has been added to give the smtp protocol startup sequence.
17. TLS on Connect Log Selector: A new log selector "tls_on_connect" provides distinguishable protocol labels for that case in received log lines. This also affects $received_protocol.
18. Pre-Config Debug Option: A command-line option for pre-config debug has been added.
19. EXPERIMENTAL_SPR_PERL Optional Build Feature: An optional build feature has been introduced, which can be enabled by the experimental.spec file.
20. Lookup Cache Control: An option to control whether lookups write the cache has been added.

Security and Notable Bugfixes

This release candidate contains fixes for the following security vulnerabilities:

• CVE-2025-26794
• CVE-2025-30232

Additionally, notable bugfixes include:

• Fix hintsdb support for dbmjz when compiled using sqlite3.
• Fix coding in SPA authenticator.
• Verify interface on when operating a continued-connection transport.
• Fix parsing of DKIM pubkey DNS record.
• Fix crash in dkim signing.

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