[Users] Claws Mail hang on one mail

[edwardp at gmx.com]

Just had another crash, this is the second straight crash using the LXQt
desktop. As was the case with last night's crash (also using LXQt), the
'uReport data' was invalid and ABRT would not report the crash.

This time, although the Claws /interface/ was unresponsive, it still
polled the accounts for mail, twice, so the interface was frozen for a
good number of minutes, before it crashed.