imap-migrate vs imapsync

imap-migrate is a free, open-source command-line tool for transferring the contents of one email folder between IMAP hosts. It can work with providers that support IMAP, including Gmail, Outlook, Fastmail, Yahoo and custom servers. The tool preserves original received dates and flags such as Seen and Flagged, and shows progress, transfer speed, success and error counts, plus estimated time remaining. It records actions in migration.log. Its README says interrupted migrations can be rerun without duplicating emails; the --dry-run option checks connection and settings without moving messages. Credentials can be supplied as command-line arguments or environment variables, with environment variables recommended by the README as the more secure option. Both accounts need IMAP access enabled, and the tool requires Python 3.12 or higher; uv is recommended for dependency management. It runs on Linux, macOS and Windows and is licensed under MIT. It does not rebuild a full folder structure or migrate provider-specific features such as Gmail labels or categories. Bug reports and contributions are invited through GitHub issues and pull requests.

imapsync is an IMAP transfer tool for migrating or backing up mailbox accounts. Its command-line software makes incremental, recursive transfers, and a stopped transfer can be restarted without generating duplicates. The software runs on Windows, Mac OS X and Linux, with listed compatibility including Gmail, Office 365, Exchange, Dovecot and Zimbra. The online service offers free mailbox syncs below 3 GB; buying provides unlimited syncs of any size. Buyers also receive a visual interface for installation on a Linux server, though that interface does not yet work on Windows. Staged and tenant-to-tenant moves are supported, including for Microsoft 365 and Google Workspace. The software-only plan is €72 as a one-time purchase; professional support is €144, paid once, as is the Imapsync + support plan. There is no trial version, and purchases carry a 30-day money-back guarantee. The tool cannot migrate contacts or calendars, maintain two-way synchronization between active accounts, or transfer messages to or from a local directory.