If I have no connection and I switch claws to offline mode, compose a message and then try to queue it, I get "Error: could not queue message". If I try to save it to draft, I get "Error: could not save draft". (If I'm not in offline mode, I just get the error that it could not connect to IMAP, then the same error as before.)

If I have a connection then both of these operations succeed, as does sending immediately. So the upshot is that I have no way to compose email without being connected.

I enabled all logging but the only messages saved in claws.log are when it is not in offline mode, saying that it cannot get to the IMAP server. My mail is stored under /media/mmc1/Claws/user/imapcache/... and I see the Draft and Queue directories there owned by user, mode 777, and I can touch a new file there. I can see Draft and Queue folders in the Claws view and in their folder properties they have the Draft and Queue property, respectively, grayed out. I have only a single account, IMAP. Downloading, reading, replying, deleting - no problem when online.  Can read and delete messages offline also. 

I tried strace on it. I see it opening and unlinking temporary files successfully in the .claws-mail/{tmp,mimetmp} directories. But comparing it with the trace of a successful queue reveals nothing; they diverge right after it closes writing something to a tmp/queue file that looks like this:

write(18, "AF:\nNF:0\nPS:10\nSRH:1\nSFN:\nDSR:\nMI"..., 656) = 656

and the file is closed successfully yet after that point everything changes and that is where the error popup comes out. I do not get this at all. There is no sign of a child process being forked.

FWIW, claws-mail is invoked via a shell script that appears to expect /usr/lib/libosso-ic-preload.so to exist, and it doesn't. But that appears completely benign. I posted this to the 3rd party apps forum on internettablettalk and there were no replies.