Until then, all mail activity on the campus mail server must be paused during file backups. The exact time this pause will occur cannot be predicted because backups are scheduled across several servers dynamically within a broad time window. All that can be stated is that the mail server will be unavailable for sending and receiving email at some point after the scheduled start of the backups. It takes 2-4 hours for a complete backup of the mail server. Complete backups are done every week and occassionally during the week.
Partial backups require considerably less time and are done every day.