I’m looking for some practical advice on exporting a very large Microsoft 365 Online Archive to PST. The mailbox contains years of historical emails, and the archive size is well over 100 GB. The concern isn’t just getting a PST created; I need the exported data to remain usable and properly organized afterward.

The first method I considered was Outlook. When an Online Archive is available in the desktop client, the Import/Export wizard can be used to select the archive and save it as an Outlook Data File. That works reasonably well for normal-sized exports, but I’m hesitant to depend on it for a mailbox containing hundreds of GB. A long-running export can be difficult to monitor, and doing multiple exports manually can take a lot of administrative time.

I also looked at Microsoft 365 eDiscovery through Purview. That seems more appropriate when the requirement involves legal discovery, investigation, or compliance. For a straightforward archival backup, though, the permissions and search/export configuration may add unnecessary complexity depending on the environment.

The other requirement is being able to export Office 365 Archive Mailbox to PST based on specific periods. If the archive spans many years, date filtering could help divide the data into manageable PST files. I’d also want the option to split oversized PSTs rather than ending up with a single huge file that becomes difficult to move or open.

While comparing available solutions, I came across the SysInfo Office 365 to PST Export Tool. It supports Online Archive mailbox exports and offers options such as date filtering, duplicate removal, and PST splitting. For a large archive, having these controls seems more practical than repeatedly running a basic export.

Regardless of the method, I think verification is an important step. Afterward, I’d check the folder hierarchy, message counts, attachments, and emails from different date ranges to make sure the export is complete.

What would you choose for a 100 GB+ archive: Outlook, Purview/eDiscovery, or a dedicated export utility? I’m especially interested in experiences with very large archives where the export had to be divided into multiple PST files.

Read More: https://www.sysinfotools.com/blog/export-online-archive-to-pst/