It seems that when moving a message into a different folder with some IMAP clients, e.g. iOS devices, a copy of the message is left behind in the original folder even though the message disappears from its original folder on the IMAP client. When I log in to WebApp the message appears in both locations. Thunderbird appears to move items properly. The default mail client on iPhone leaves behind a duplicate copy. I haven’t yet tested this with any other clients. This behaviour didn’t occur with Zarafa, I’ve only noticed it since a recent switch to Kopano. It also doesn’t occur when accessing a different IMAP server (Dovecot) from the same iOS device.
When flagging a message using IMAP, it used to apply a flag. It now applies a tag. I gather that flags now mean due dates and tags mean category, which is a bit confusing.
There are some other glitches when accessing mail via IMAP with an iOS client. Most annoyingly, occasionally while viewing a message, the iOS mail client decides that the message is part of a thread containing every other message. Again, this doesn’t happen when using iOS to access Dovecot-backed IMAP accounts.
And if anyone is wondering why I’m using IMAP instead of Z-Push on an iOS device, it’s because Z-Push no longer works following our switch from Zarafa to Kopano and local install of Z-Push to the packaged version. I’ll be posting a separate thread about that.