Exim 4.100-RC2 was released on August 5, 2026, marking it as the definitive version ahead of the final 4.100 release, with only minor fixes and enhancements. Key features include new psl and regdom lookups for Public Suffix manipulation, a native DMARC evaluation switch, and improved logging options for authentication. The release also emphasizes a new development model, separating stable releases and security patches from ongoing developments, while explicitly rejecting contributions from AI-generated sources. Security improvements were made to address critical vulnerabilities, indicating a focused approach to maintaining the integrity and trust of the open-source project
Exim 4.100-RC2 Drops: Native DMARC, PSL Lookups, and Security Bundles Signal the Final 4.100 Release
Exim 4.100-RC2 shipped on August 5, with the maintainers explicitly closing the sourcebase to treat the candidate as the definitive 4.100 release. The unusually tight six-day gap from RC1 reflects high confidence in the codebase, as RC2 delivered only fixes, compiler quietening, and essential Proxy Protocol and DMARC hardening. Headlining the feature set are new psl and regdom lookups for Public Suffix manipulation, a native EXPERIMENTAL_DMACR_NATIVE build switch, and granular authentication logging selectors. Alongside the code changes, the project formalized a split development model and drew a hard line against LLM-generated contributions, with vulnerability credits now referencing AI training data.
