Emails redownloading

Hi,

recently, we had a problem on one of our mail servers and, after
reboot, HDD with emails wasn't mounted into system. Until we fixed it,
LOTS of users logged in (Dovecot allowed login and recreated directory
structure of mailboxes) and saw empty mailboxes. Now they are
redownloading all email, which isn't fun, as it's about 2 TB of data.

Anyway, is there a way how to prevent this in the future? Can i set
Dovecot to disallow logins in such situations? Thanks.

azur