Finally, I've bought a wildcard ssl for zimbra to resolve the issues with mobile apple devices.
But, as feared, I quickly ran into trouble with it.
I choose "Comodo Positive Wildcard SSL" via SSL2buy provider - because all those ssl things look alike to me and this was one of the cheaper ones.
Wildcard because the mail, web and application server are on different hosts.
The mail server is a local server.
For the configuration I followed https://support.sectigo.com/PS_KnowledgeDetailPage?Id=kA01N000000zFKL Other guides show similar instructions.
I got stuck at the CSR validation, where the site complains that "CSR with SAN is not allowed"
I recreate the csr via zimbra adminpage making sure the SAN was removed.
the error stayed the same.
I tried some iterations with the common name, to no avail.
zimbra: Zimbra 8.8.15_GA_3847 (build 20190823100304)
zimbra server: truckle.domain.com
intended certifcate for: *.domain.com
A similar issue was raised here on the forum https://forums.zimbra.org/viewtopic.php?f=15&t=60490&hilit=ssl+san+wildcard, but without solution.
I rather not mess with commandline unless I'm sure I won't break zimbra.
Suggestions are very welcome to overcome my fear of certificates

glenn