is it safe to run current Ciphermail version on Debian 11 or even 12?
Documentation only states that supplied packages are tested with Debian 10.
Debian 11 is supported. Unfortunately CipherMail currently requires Java 8 or 11. Debian 12 only supports Java 17 out of the box. If Debian 12 is required, you might try to install OpenJDK 11 from https://adoptium.net/ (I have not tried this)
We are currently working on upgrading the gateway to support Java 17+. There is however no release date yet.
Thanks for your information. Upgrading to Debian 11 is OK for our installation.