No idea about your Icedove problem but... It does not? That's new to me. It works perfectly fine for me. What Modest does NOT do is put your sent emails in the proper "Sent" folder. Instead, it puts them all in some local "Sent" folder.. All sent emails from all accounts go the same one place, all mixed up. Yuck. So the first thing I do after sending an email is reopen the message, select "Move Message" from the menu and move it to the relevant account's "Sent" folder where it is nicely synced with my IMAP server.