Emails redownloading

[azurit--- via dovecot]

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