I've upgraded from Debian11 to Debian12 (bookworm( with the Testing-Repo added.

The good news is that sending and receiving mail works well. I'm struggeling with roundcube (my users access with snappymail - that works) and webadmin.

Let's have a look at webadmin:

# dpkg -l kolab-webadmin
...
ii  kolab-webadmin 3.2.16-0~kolab2 all          Kolab administration web interface

The first thing I noticed is that 3.2.26 has been release in 2021:

Tag: kolab-webadmin-3.2.16 d2f531414aa7·Release 3.2.16·machniak on Nov 8 2021, 14:11.

In the meantime there have been lot's of changes, e.g. php8 fixes. I think it's time to cut a new release.

[currently the git history in phabricator is broken...]

The Debian packages has these dependencies:

Depends: apache2, libapache2-mod-php | libapache2-mod-php5, ldap-utils, php-http-request2, php-mail, php-net-ldap2, php-net-ldap3, php-net-smtp, php-net-url2, php | php5, php-mysql | php5-mysql, smarty3 (>= 3.1.7)

Since php5 is long gone, these dependencies should be removed.

I'm also unsure why both php-net-ldap2 and php-net-ldap3 are needed.

It might also be useful to move to smarty4.