Mailman

I know that ISPConfig only supports Mailman 2. Mailman 2 is still listed as stable Mailman version. Besides, it's easy to install Mailman from Buster under Bookworm. However, while trying, I found a bug in the code used to install Mailman which I solve using the provided merge request.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information