I’ve noticed that older PST archives often contain much more data than users actually need. There can be years of emails, outdated attachments, duplicate messages, and folders that are no longer relevant. Because of this, I’m wondering whether filtering PST data before moving it to Microsoft 365 is a better approach than transferring everything.

A simple starting point would be identifying the date range that needs to be retained. For example, an organization may only require emails from the last few years while keeping older archives separately. This can significantly reduce unnecessary data being processed during the migration.

The SysInfo PST to Office 365 Migration Software  caught my attention because it provides a Date Filter for selecting emails between a specified start and end date. It also allows users to preview PST emails and attachments before migration, which seems helpful when deciding exactly what should be transferred.

Attachments are another consideration. Some PST archives can contain large files that are no longer required. Having an option to exclude attachments could help reduce unnecessary mailbox data when attachments aren't part of the migration requirement.

Duplicate messages can also become a problem when several PST archives overlap. Removing duplicate emails based on properties such as To, From, Bcc, Subject, and Body can help prevent the destination mailbox from becoming unnecessarily cluttered.

The import PST to Office 365 tool approach therefore seems worth considering when administrators want more control over which data reaches the destination mailbox. I would still recommend running a small test first and checking the resulting folder structure and message content.

For a larger PST to Office 365 migration, data selection should ideally be decided before the transfer begins. Otherwise, administrators may spend additional time cleaning the destination mailbox afterward.

How do you normally handle old PST archives? Do you migrate the complete files and clean them later, or filter emails and attachments before importing them into Microsoft 365?