hlhd/isync repository overview

⁠📬 isync

isync⁠, the project behind the mbsync command, in a small rootless image: two-way synchronization between two IMAP servers, or an IMAP server and a local Maildir. It keeps state between runs, so moves, flags and deletions on either side reach the other.

⁠Usage

The image runs mbsync (Alpine, isync 1.5.1) as UID 65532 and accepts any UID in group 0, with a read-only root filesystem. Mount a config and a writable state directory, and let the platform schedule it (a Kubernetes CronJob or a systemd timer); nothing in the image runs on a timer. Arguments starting with - go to mbsync; any other command (sh, a script) runs as given.

docker run --rm --read-only \
  -v ./mbsyncrc:/etc/mbsyncrc:ro \
  -v ./secrets:/run/secrets:ro \
  -v mbsync-state:/var/lib/mbsync \
  hlhd/isync -c /etc/mbsyncrc -a

• /var/lib/mbsync: sync state. Keep it between runs; without it the next run cannot tell a deletion from a new message.
• Passwords come from files at run time, never from the config: PassCmd "cat /run/secrets/<name>".
• TLS 1.2 and 1.3 only, certificates verified.

Two-way sync between two IMAP servers, here a Gmail account and a self-hosted mailbox:

IMAPAccount gmail
Host imap.gmail.com
User [email protected]
PassCmd "cat /run/secrets/gmail"
TLSType IMAPS
TLSVersions +1.2 +1.3

IMAPAccount home
Host imap.example.com
User [email protected]
PassCmd "cat /run/secrets/home"
TLSType IMAPS
TLSVersions +1.2 +1.3

IMAPStore gmail
Account gmail

IMAPStore home
Account home

Channel mail
Far :gmail:
Near :home:
# Gmail shows every message under "All Mail" and again under each label;
# syncing it would duplicate everything.
Patterns * !"[Gmail]/All Mail" !"[Gmail]/Important" !"[Gmail]/Starred"
Create Both
Remove Both
Expunge Both
Sync All
CopyArrivalDate yes
SyncState /var/lib/mbsync/

⁠License

isync is GPL-2.0-or-later; this packaging follows it.