What the upgrade involved

No schema change: 6031, as 6.2.27. The installer's database upgrade has nothing to do on a 6.2.27 database.

Everything this release adds is off by default. UpdateCheckEnabled, RestApiPort (which the portal and the Control Deck need), IMAPCompressionEnabled and HttpProxy are all opt-in. A server upgraded without touching its settings behaves exactly as 6.2.27 did.

Known and unfixed: the Control Deck reads but does not write, and holds the administrator password in sessionStorage while it is open. The regression suite runs on Windows only.

What is in it

• Updates. UpdateCheckEnabled=0 is the default and nothing happens until it is set: no request, no identifier, no counts. Turned on, the feed is read every UpdateCheckHours (24 by default). An installer is verified against its Sigstore bundle before it runs: the certificate chains to Fulcio, the identity and issuer are this project's release workflow, and the entry is in the public transparency log. These releases are not Authenticode-signed, so UpdateRequireAuthenticode=1 refuses every one of them, and the Sigstore check cannot be turned off. hMailServer.Updater.exe stops the service, waits UpdateServiceWaitSeconds (180) for it to come back, and reinstalls the previous version if it does not.
• Webmail. /portal on the REST listener, with /api/v1/me behind it. It answers to the account's own credentials only: no administrator password, no API key. Read, send, search, attachments, the account's own quarantine, Sieve script and password change.
• A real HTTP server. The REST API and web services move off a single-threaded HTTP/1.0 loop onto HttpServer: HTTP/1.1 on Boost.Asio with keep-alive, chunked bodies, and header and body deadlines.
• IMAP COMPRESS=DEFLATE (RFC 4978). Advertised until compression is on and refused afterwards, as the RFC requires. STARTTLS is refused once a session is compressed.
• HttpProxy=host:port sends every web request the server makes as a client through a forward proxy. CONNECT for https, with the same certificate verification as a direct connection. No proxy credentials.
• Fixed (#156). A masked password in the Control Panel was typed backwards from the second character: 12345678 became 18765432. It hit IME commits and some keyboard layouts.

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