Any attempt to save emails in Thunderbird produces the "Unable to save your message as draft" message box, and sending fails similarly with "Sending of message failed".
(I've checked the obvious. Folders were all compacted/repaired recently. There is no actual flaw in the profile email settings, and the problem persists in a new profile.)
- OS is Win XP Home.
- The problem does not occur for other Thunderbird users with logins on the same machine; it is specific to this user.
- The problem does occur even in a new, blank Thunderbird profile created for this user.
I assumed it was a file corruption issue in the profile, but it can't be if it happens in a new profile. Does anyone have any debug suggestions?
Problem solved; ChrisF was on the right track. The Windows Temp directory environment variable for the user identity had been changed to a nonexistant path, so Thunderbird couldn't create temp files. Correcting this solved the problem.