One thing I’m concerned about with an upcoming IMAP-to-Office 365 migration is the mailbox structure. We have years of email organized into Inbox, Sent Items, Drafts, Deleted Items, and several custom folders. There are also plenty of attachments that users need to access afterward.

I don’t want to finish the migration only to discover that everything has been dumped into one folder or that attachments and email metadata were lost.

I found the DRS Softech IMAP to Office 365 Migration Tool, which specifically supports maintaining the folder hierarchy and transferring attachments along with the associated messages. It also preserves properties such as sender, recipient, subject, date, time, and read/unread status.

The preview option is another useful part because it lets you review folders, subfolders, email details, and mailbox counts before actually starting the transfer.

Has anyone dealt with a similar migration where preserving the existing mailbox organization was a priority? What did you use to verify the folder structure afterward?