Most threads that take a week take a week because the first five replies were spent establishing which version is running. Paste the block below at the top of your post, fill it in, and the first reply you get can be an answer.
The template
hMailServer version: 6.3.3.42 (Windows) or the exact package version (Linux)
Platform: e.g. Windows Server 2022, Debian 13 x86-64, Ubuntu 24.04 AArch64
Database: PostgreSQL 16 / MariaDB 11 / MySQL / built-in
How it got here: fresh install, or in-place upgrade from 5.6.8 on 12 September 2026
Control Deck, webmail or REST API enabled: yes or no (RestApiPort in hMailServer.ini)
Anti-spam in use: SpamAssassin, SURBL, DNSBLs, greylisting
What I expected to happen:
What happened instead:
First seen: date and time, and what changed immediately before that
Already tried:
Log excerpt, timestamps intact and credentials redacted:Version, exactly
Three parts and the build stamp, not the latest. 6.3.3 and 6.3.3.42 are different things to say, and 6.2.24 or earlier is a real answer if that is where you are. If you are not sure, the version is on the Control Panel dashboard on Windows and in the Control Deck at / on either platform.
Logs beat descriptions
Raise the log level before you reproduce the fault, reproduce it once, then take the window around it — the SMTP, IMAP, POP3 or application log as applicable. Leave the timestamps in; they are how anyone reading works out ordering. Paste it in a fenced code block rather than as a screenshot, and strip the AUTH lines, API tokens, DKIM private keys and third-party addresses first: the forum is public and indexed, and a credential pasted here is a credential to rotate.
Check these before you post
- Is it fixed already. Twenty releases shipped between 12 August and 15 September 2026, and every one of them lists exactly what changed — release notes on the downloads page.
- Is it the upgrade. There is one open defect in the upgrade path and it fails loudly and rolls back rather than doing anything quietly — the upgrade chapter.
- Is it DNS. It is very often DNS — DNS and deliverability.
- Is it certificates or transport security. TLS 1.2 and 1.3 only, with MTA-STS, DANE and DNSSEC validation enforced by default for outbound mail — encryption and certificates.
- Is it a platform limit. No Control Panel and no COM on Linux, and per-domain DKIM cannot be configured there yet — the Linux chapter.
Where things live
- The webmail and the Control Deck — chapter 36
- The REST API — chapter 24
- Rules and Sieve — chapter 12
- Monitoring and health — chapter 16
- Security hardening — chapter 17
- Version history — chapter 25
Then post it in the right place
Mail not arriving, queues, certificates and installs go in Support › General discussions. COM, the REST API and scripts go in Scripting. Filtering goes in Anti-spam and SpamAssassin. Something you want built goes in Development › Feature requests. A reproducible defect goes on GitLab, linked from the thread.
If the answer turns out to be interesting, write it up afterwards in User-submitted tutorials. That category is how this forum stops being the same twenty questions.