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isyncfdm
Free

Free and open source under the GPL.

 Free

Free, with the source code published on GitHub.

Windows, macOS, Linux, Command line macOS, Linux, Command line
  • Much faster than Python-based synchronisers on large mailboxes
  • Precise control over which folders sync and in which direction
  • Combines fetching and filtering in one program
  • Delivers to Maildir, mbox, IMAP, LMTP or a pipe
  • Configuration syntax is terse and mistakes can delete mail
  • Command line only
  • No interface for reading mail
  • Configuration takes time to learn
Downloadable app Downloadable app
Open source Open source
License: GPL-2.0 License not stated
Not stated if an account is needed No account needed
Not stated if it works offline Not stated if it works offline

Checked September 22, 2026

Checked October 1, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.