How do you safely back up IMAP emails before moving to another service?

General Discussions
1

I’ve seen a lot of questions about the safest way to back up an IMAP mailbox before changing providers. The manual approach can get messy, especially when there are multiple accounts or years of email involved.

I’d personally look for a tool that can save IMAP mail into commonly used formats such as PST, MBOX, PDF, EML, MSG, CSV, DOC, or DOCX, while keeping the original folder structure and data intact. That gives you a local copy even if something goes wrong during migration.

For larger environments, being able to process multiple mailboxes at once is a big advantage. A preview option is also useful because you can open the mailbox, review folders, and select only what you actually need.

I also think duplicate handling is important. A good backup utility should be able to identify identical messages using criteria such as To, From, Subject, and Body rather than creating another copy of everything.

One option I came across is MacSonik IMAP Backup Tool. It supports Mac and Windows and can move IMAP data directly to Gmail, Office 365, Google Workspace, or another IMAP account. It also offers date-based filtering, attachment control, separate PDF attachment saving, mailbox cleanup after backup, and PST splitting for large files.

Has anyone here used a dedicated IMAP backup tool rather than relying on an email client?

2

The safest way is to take a local copy of the IMAP mailbox before starting the migration. That way, the original emails are still available if some messages, folders, or attachments do not transfer correctly.

For a small mailbox, syncing it with an email client and saving a local copy may be enough. With larger mailboxes, this can take longer and depends on the client completing the sync properly.

I’d use GainTools Cloud Backup Tool when I need a separate backup before moving the account. It can save IMAP emails in formats such as PST, MBOX, EML, EMLX and MSG, depending on how the backup will be used later.

I would check the backup before deleting or changing anything on the source account, especially a few emails from different folders and their attachments.