Help with IMAP access to Kolab mailbox

[Wilhelm]

I am trying to access a Kolab mailbox from Thunderbird using IMAP via
Cyrus. I have run into trouble as Cyrus does not seem to acknowledge the
wildcard certificate that I have acquired from Comodo.

I am using Kolab 3.2 with Cyrus 2.5 on an Ubuntu server and have tried
to follow the instructions on the following page
https://docs.kolab.org/howtos/secure-kolab-server.html but without
success. I am able to access the mailbox but have to add an exception on
IMAP (I have managed to activate SSL for SMTP/Postfix).

Any help would be greatly appreciated.

Kind regards,

Wilhelm