Glossary
PST file
The file format Outlook uses to store mail, contacts and calendar items offline.
ValidReach Team · Updated 2026-10-26
In practice
It is used for archives and backups and for moving mail between accounts. The file can be very large, and older formats have size limits.
Verification and sending
Contacts exported from a PST are people you corresponded with, not people who agreed to marketing. Check the legal basis before using them.