This was an alpha. Everything in it shipped in 6.2.24. Nothing here should be installed today.
Thunderbird 128 and later could not save a single Sent copy. Every message went out over SMTP and nothing was ever stored, with only a per-machine client setting as a workaround (GitHub issue 53). Two ways a sender could steer the anti-spam tests are also closed here.
What the upgrade involved
This is an alpha because one of the fixes changes what a non-conforming client sees.
Relayed and fetched mail is now tested against a different address. The Received parser takes the last observed address before by, ignores values marked as HELO-supplied, and keeps a header whose host name is not a valid domain name. If you sit behind an incoming relay and have tuned scores around the old behaviour, expect verdicts to move.
MAIL FROM straight after a STARTTLS handshake with no fresh EHLO now gets 503 Bad sequence of commands, as RFC 3207 section 4.2 requires. If you have a home-grown submission script that skips the second EHLO, this is the release that tells you.
Changes
IMAP APPEND: once a client enables UTF8=ACCEPT, RFC 6855 lets it wrap the message as UTF8 (~{n} plus a closing ). The parser counted parentheses across the whole line and refused with BAD APPEND Command requires at least 2 parameter before reading a byte. The wrapper is now stripped ahead of the parser, including the non-synchronizing ~{n+} form and later messages of a MULTIAPPEND.
Anti-spam bypass: the parser took the first bracketed value after from, which is the HELO literal the client chose, and skipped any header whose host name was not a valid domain (my_pc). DNSBL, SPF and the HELO-host test could be skipped entirely. Two assert(0) on sender-reachable input are gone with it.
RSET before EHLO no longer opens a transaction on its own. That had let MAIL FROM through with an empty HELO host, skipping the OnHELO/OnEHLO events.
A PTR answer carrying the trailing dot (1.0.0.127.in-addr.arpa.) no longer empties the result. That had been failing open in the HELO and reverse-DNS spam tests.
hMailServer.exe is built with /guard:cf in both configurations (GitHub issue 45).
An unattended install whose database step fails now fails, rather than showing a suppressible message box and exiting 0.
Known limitation: the weekly C++ CodeQL analysis has not run since late August. It targets a self-hosted runner that is no longer registered.
Full release notes, checksums and signatures
