The current release of the Mailserver is version 4.6
The previous release of the Mailserver is version 4.5
All releases version 4.4 and earlier has reached end of support, please upgrade to at least version 4.5
Please use the previous release of the Mailserver if what you're looking for is an absolutely stable release that has been tested and proven over a long time, or wait at least a couple of months after each major release.
A couple of things to note with the development of the Mailserver:
The Mailserver follows the development cycle of OpenBSD with a major upgrade twice a year. A new version of the Mailserver is typically released 1-2 months after the release of the latest version of OpenBSD.
New features happens with the release a new major version only, there are no ongoing feature releases of the Mailserver between the major releases.
Only important security fixes will be updated between releases, i.e. something that has the potential of causing data loss or a remote execution vulnerability.