GW2014SP2 - cached mailbox, send items moved to trash

Hi all,
Just after moving to GW2014 SP2 one of users have problem:
He is working on laptop on chached mailbox. When sending mail, after 30-40 seconds he gots info, that email couldn't be sent and is moved to trash.
Send from online works properly.
Recreated cache (deleted whole folder) on the same computer and reinstalled GW client - not solve the problem.
Anyway caching was working very long - on 1GB (local lan) it takes 4-5 hours to synchronize 15GB mailbox (usually, but before moving to SP2 it was 15-20 GB/hour) - at this moment I don't know if recreate is slow only on this mailbox or slow down generally (also checked on second computer - and speed of creating cached mailbox is the same).
Cause up to midnight cached mailbox on second computer was not created - I couldn't check if sending problem exist on other computer.
Computer Win7 64 bits.