Important: It is strongly recommended to have a mailbox size lower than 50 GB.
If a mailbox size is bigger that limit,
In Outlook Backup service there is also a hard limit set for creating and restoring PST files - 50 GB.
If you need to create a PST
To do this, navigate to Service > Outlook Backup and follow those steps:
1) In Outlook Backup click Create Backup.
2) Choose One-Time and uncheck Full backup button.
3) Set a Date range to be limited approximately to the middle of your mailbox usage time period.
4) Add necessary mailbox to backup.
5) Click Create Backup.
6) Once the backup is created, perform steps 1-5 again, but setting a Date range from the middle usage time period until the current date.
Note: Outlook Backup will also fail to restore a PST larger than 50 GB, so you will need to make a restore with PSTs