Обсуждение на форуме тут: http://www.forum.nobat.ru/index.php?topic=5949.0
What´s new in 4.0.26.2 since 4.0.26.1:
[ * ] Users might find some SMTP/POP3 tasks in in Connection Center hanging; deleting them didn´t produce a result. These hanging tasks might have been caused by unhandled errors (exceptions). Now such errors are being logged in the account log.