(Note that 4.1.0 (build 4024) - 05 June 2024 remains available, but usage of this version is not recommended - particularly for Davis stations - and the included utility in this distribution for migrating to v4 is known to contain errors affecting conversion of dayfile.txt)
Legacy Cumulus 1 release 1.9.4 (build 1099) - 28 November 2014
(a patch is available for 1.9.4 build 1099 that extends the date range of drop-down menus to 2030)
Download the Software (Cumulus MX / Cumulus 1 and other related items) from the Wiki
From build 3044 the development baton passed to Mark Crossley. Mark has been responsible for all the Builds since. He has made the code available on GitHub. It is Mark's hope that others will join in this development, but at the very least he welcomes your ideas for future developments (see Cumulus MX Development suggestions).
You may need to twist your package manager's arm in order to get it to install a later version that the official one for your distro - if that is the case, them this guide may be useful.
I would try sudo apt update && sudo apt upgrade first though - it may pick up 6.12.
Latest release 3.25.1 (build 3244) working on 64bit Bullseye for me with mono 6.8.0.105
During my trying to fix 3241 on 32bit Bullseye I lost my SSD, rebuilding on a new one gave me a chance to start from scratch and I tried running on the standard install mono before fiddling it, and it worked
I didn't mean email in general - I meant email functions as used by Cumulus in its alarm functionality for example. But if you're happy sticking with the old version as you don't use that part of Cumulus then that is fine.