Hm, in the meanwhile I switched to Thunderbird again so I can't try it anymore. But maybe this solves a lot of other people's issue.
When I encountered this problem, I had imported my config from an old Evolution's backup. Apparently "IMAP+" is the same IMAP but a better implementation in Evolution. If this is the case, then why does the import assistant not ask me whether I want to use the new implementation or the old one? Maybe it could even switch my accounts to the new implementation anyways without even asking me...
Hm, in the meanwhile I switched to Thunderbird again so I can't try it anymore. But maybe this solves a lot of other people's issue.
When I encountered this problem, I had imported my config from an old Evolution's backup. Apparently "IMAP+" is the same IMAP but a better implementation in Evolution. If this is the case, then why does the import assistant not ask me whether I want to use the new implementation or the old one? Maybe it could even switch my accounts to the new implementation anyways without even asking me...