There is no direct technique to add an OST file in Outlook. If you also want to know how to add an OST file in Outlook, read this write-up till the end to find the best way to solve your query.
Outlook supports two file formats OST and PST. The OST file allows us to access our emails, contacts, calendar, journals, etc. in offline mode.
When you add a new email account in Outlook, a mailbox copy is automatically saved on your local drive. A mailbox copy saved in offline mode is known as OST file (Offline Storage Table). Outlook automatically resynchronizes your data when will you come back online again.
Reason to Add OST file in Outlook
1. Exchange server downtime can occur for several reasons: malware attacks, viruses, and hardware/software failures. To restore backup OST files in bad time when disaster/downtime happens.
2. When we put the Exchange server in maintenance mode, we cannot access our mailboxes so users have to import an OST file into Outlook to access it.