Understanding PST to Office 365 Incremental (Delta) Migration and Why It Matters

PST to Office 365 (M365) migration rarely goes as smoothly and clean as you planned, even after taking care of all the prerequisites. You start the migration process and the mail items from PST files to mailboxes on the cloud platform start moving. By the time it reaches halfway mark, the process gets interrupted or even failed due to network connectivity issues or throttling bottlenecks. In this situation, you need to start migration from the start, lead to duplicating items and increased administrative efforts and time. This is the problem that you can resolve with incremental migration. In this article, we will explain what incremental migration is, why it matters, and how a specialized PST to Office 365 migration tool helps to perform it.

What is Incremental Migration?

Incremental migration, also known as delta migration, means the process to migrate the items that are new or modified since the last migration, rather than starting the process from scratch. In simple terms, it skips the items that are already transferred and migrates only those that are new or have changed. This avoids duplicate items and considerably reduces administrative efforts and time as only the items which are left in the previous run are moved.

When should you Choose PST to Office 365 Incremental Migration?

While migrating PST files to Office 365 (Microsoft 365), incremental migration can help in the following scenarios.

Importing Large PST Files: Importing large PST files into Microsoft 365 requires significant time and network bandwidth. If the process gets interrupted, you will need to re-import the complete PST files, leading to duplicate emails and waste of time and bandwidth. In this situation, incremental migration can help you import only the remaining items in the file.

Multi‑phase Migrations: When you’ve to move large amounts of data in phases and need to run the process multiple times, you can perform incremental migration. This means you can run the process more than once without worrying about duplicating data.

Bandwidth Constraint: If you’re migrating PST files to Office 365 from a location with limited network capacity, uploading large files multiple times is not possible. As the incremental process allows you to transfer only new or modified items, it reduces network load and speeds up the migration process.

Projects Requiring Multiple Passes: When validation, testing, or phased rollouts require several migration attempts, incremental migration ensures each run only moves what’s necessary.

Why Incremental (Delta) PST Migration Matters?

Incremental migration is important when migrating PST files to Office 365 because it:

Prevents Repetitive Data Transfer if Migration Stops: If the PST to Office 365 migration process is interrupted or stopped, incremental migration allows you to skip the items that were transferred in the previous run. This helps prevent repetitive data transfer and duplication of emails and other items.

Saves Time and Bandwidth: With incremental migration, you can transfer only new or modified items instead of migrating the entire PST file after the process interruption or restart. This helps save time and reduce bandwidth consumption, especially when migrating large PST files.

How to Perform Incremental PST Migration to Office 365?

Microsoft offers two native methods, Network Upload and Drive Shipping for importing PST files into Office 365. But these methods do not support incremental migration. However, you can use a professional tool, Stellar Migrator for Outlook , that allows quick and smooth transfer of PST files data to mailboxes on Office 365 by preserving the original folder hierarchy and structure. It also supports incremental migration to ensures that only new or modified data is imported when you re-run the migration process. It automatically skips already uploaded items, thus preventing duplicate items.

Trusted by IT Admins and MSPs, Stellar Migration for Outlook can bulk import PST files with automatic and customizable mailbox mapping by using a CSV file. It can also migrate PST files from a single or multiple systems, independent of the location. This PST to Office 365 migration tool shows real-time progress of migration process during and after completion. 

Conclusion

Incremental or delta migration is beneficial when you need to re-run the migration process in case of any issue. As the native migration methods provided by Microsoft do not support delta migration, you should opt for a third-party PST migration tool, such as Stellar Migrator for Outlook. It provides an incremental migration feature that allows you to migrate only the new or modified items from PST files to Office 365 mailboxes when you re-run the process.