New user, error "copying to Sent folder"

Running Ubuntu. Signed up for Librem.One Complete. Started Thunderbird for the first time. Put in my email address, it auto-detected settings, I chose IMAP, and was up and running fast.

First action was to test it by sending an email to my gmail. The email went through fine, as did my response email.

The problem is, the window with my email draft never closed because the popup dialog with “Copying message to Sent folder…” never finished.

Anyone know if this is due to some kind of mismatch of expectations between how Thunderbird expects IMAP folders to be set up and how Librem.One IMAP is set up? Or perhaps a folder permissions problem? Just a blind guess - I’m no email expert.

That happens to me with Libem Mail A LOT. Usually when there is a big attachment.

(It never happens with gmail by the way).

When it happens I have to force myself to let it time-out. Then Thunderbird with ask me if I want to save it in a local folder instead. (Which also tells me it is in a cache somewhere.)

I think it has to do with IMAP sending you back a copy of what you just sent for your sent folder. I guess it is the way it is supposed to work but it seems a remarkably inefficient bandwidth use.