I’m currently researching Microsoft 365 migration planning and one question keeps coming up: should an organization create a complete backup before moving its mailboxes to another cloud platform? In my opinion, this depends on the amount and importance of the data involved, but for a business with years of emails and attachments, having an additional copy seems like a sensible precaution.
When companies migrate Office 365 to Google Workspace, they have to deal with several types of mailbox information rather than emails alone. Contacts, calendars, attachments, archive mailboxes, and folder structures may all need attention. Account mapping is another important area because a mistake in the source-to-destination relationship could send mailbox data to the wrong user. Authentication and permissions should also be tested before the main migration begins.
Another practical concern is the migration window. Employees may continue receiving new emails while administrators are transferring the existing mailbox data. This means that the first migration pass may not contain everything by the time the project is completed. Incremental processing can be useful in this situation because administrators can identify previously transferred items and focus on newly added data instead of repeating the entire operation.
A backup can also provide an additional layer of protection if something unexpected happens. Accidental deletion, configuration errors, retention problems, or other issues can become difficult to resolve when there is no independent copy of the mailbox data. For this reason, I have been looking at Office 365 Backup Software that can handle primary mailboxes, archive mailboxes, and public folders while maintaining the original folder hierarchy and email properties.
Another feature I would consider important is selective backup. Not every organization needs to export every message every time. Date filters can help administrators select emails from a specific period, while duplicate removal can prevent repeated messages from unnecessarily increasing the backup size. Exporting data to formats such as PST, EML, MSG, MBOX, PDF, or CSV can also be useful depending on the recovery or archival requirement.
While comparing different options, I came across the DRS Softech Office 365 Backup Tool. Its product information mentions Modern Authentication, Client ID support, automatic and CSV-based mailbox loading, mailbox preview, incremental backup, duplicate removal, advanced date filtering, PST splitting, and flexible destination options.
For those who have handled Microsoft 365 migrations, would you recommend creating a full backup before beginning the migration? I’d also be interested to know whether you performed the backup for all users at once or divided the process into smaller batches.