I need to migrate two personal Gmail accounts into Microsoft 365. One contains less than 500 MB of mail, while the other is around 15 GB. I'd like to preserve Gmail labels if possible, ideally by mapping each label to a subfolder in the Microsoft 365 mailbox. I know Microsoft 365 doesn't use Gmail-style labels, so I'm looking for a practical free or paid migration method. Google Takeout followed by converting MBOX to PST is one option, but I'm hoping there's a cleaner alternative.
3 Answers
The native Microsoft 365 IMAP or Google migration tools may be worth checking, but support for ordinary personal Gmail accounts and label preservation can be limited. For a personal account, the Thunderbird-to-IMAP method is generally the safer choice when folder structure matters.
Before moving the 15 GB account, hide Gmail’s “All Mail” folder from IMAP if possible. Gmail applies All Mail to nearly every message, so copying it can create duplicates and consume a lot of space. Also watch for messages with multiple labels, since they may be copied into multiple destination folders.
A straightforward approach is to use classic Outlook with Gmail connected through IMAP, then copy the messages into the Microsoft 365 mailbox and export or import through PST if needed. This can work well for the smaller account, although it may be slow and manual for 15 GB.
Thunderbird is probably the better option if preserving labels matters. Import the Gmail MBOX into Thunderbird so the labels appear as local folders, connect the Microsoft 365 mailbox through IMAP, create the matching subfolders, and drag the messages over. It isn’t very automated, but it gives you control over how labels are mapped.
Personal Gmail no longer has the old IMAP enable/disable switch in many accounts; IMAP is simply available. That still doesn’t guarantee the Microsoft migration tools will preserve labels, though.