Use IMAP sync to migrate Gmail emails to Office 365

Use IMAP sync to migrate Gmail emails to Office 365. That is the clean answer, and it is the one that still holds up when the mailbox has to move without turning into a science project.

I keep coming back to the same plain fact. IMAP is the common lane here. It lets Office 365 read mail from Gmail and copy it over. Microsoft’s current setup notes say Office 365 can connect to Gmail with an IMAP migration endpoint, and Gmail must have IMAP turned on first. That is the core of the move.

The job is simple in shape, even if it is not always simple in practice. Office 365 makes a connection to Gmail, checks the mailbox, and pulls mail across folder by folder. The main point is that the mail stays in mail format. There is no need to strip it down and rebuild it into something else first. That is often why IMAP is chosen for this kind of transfer.

There is one detail people miss at the start. IMAP migration is about email, not the whole account. Microsoft’s migration guidance says IMAP moves the messages in mail folders, but not contacts, calendar items, or tasks. That matters because a mailbox can look “done” after the mail lands, while the rest of the user’s data is still sitting somewhere else. Mail is only part of the story.

That is why I treat this as a mailbox move, not a full life move. Gmail to Office 365 by IMAP gets the email content across. It does not promise to rebuild every part of the old account. If the goal includes contacts or calendar data, that part needs a separate path. IMAP is honest that way. It does one job and does not pretend otherwise.

The other practical point is Gmail setup. Gmail or Google Workspace has to allow IMAP access before the transfer can begin. Microsoft’s current guidance says to enable IMAP in Gmail settings, then create the migration endpoint in the Exchange admin center and point it at Gmail’s IMAP server. That server is imap.gmail.com. Small detail, large effect. Mail systems are full of tiny doors like that.

There is also a limit that deserves a clear line. IMAP migration does not solve every messy case. If a mailbox has odd folder names, very large mail sets, or old items that were never really healthy in the source account, the move can still stall or leave gaps. A migration tool can copy what it can reach. It cannot make bad source data behave itself. Mail, like people, keeps its own habits.

I also like to say this out loud because it saves time later. A finished sync is not the same thing as a finished migration. The export or copy may end with no error and still miss something important. Folder counts can drift. A message may sit in a place the sync did not map well. Contacts may never move at all because IMAP does not carry them. The mailbox may look tidy and still be incomplete.

So the real answer is plain. Use IMAP sync to migrate Gmail emails to Office 365, because that is the built-in path Microsoft supports for Gmail mail transfer. It is the right fit when the task is email only and the goal is to move messages and folders into Microsoft 365 mailboxes. It is not the full answer for every piece of account data, and it should not be treated like one.

A careful move still starts with the source mailbox being ready. Gmail must allow IMAP. Office 365 needs a mailbox for each user before the migration. The connection then has to be tested before the batch runs. That is boring work, which is usually a good sign. Email migrations often fail because someone skipped the boring part and hoped for a miracle. The mail gods do not care.

The honest middle ground is this. IMAP sync is the standard, practical way to move Gmail mail into Office 365. It is well supported, direct, and familiar to anyone who has moved mail before. But it is not magic, and it is not complete for every data type. If the mailbox matters, the check at the end has to be simple and stubborn: every message, every folder, and every needed item accounted for.

That is the kind of work The Migration Brief is built for. One practical fix, one file format explained, and one safer way to move your mail.