docker-isync

Dockerized isync.

isync syncs an IMAP mailbox to a Maildir (emails as individual files), in contrast to imap-backup which syncs an IMAP Mailbox as .mbox backup files. Additionally, isync can also sync two IMAP mailboxes.

Tags

Tag	Dockerfile Build Context
:1.4.4, :latest	View
:1.4.4-pingme	View
:1.4.4-restic	View
:1.4.4-restic-pingme	View

• restic: Includes restic. Useful for cron-based backups.
• pingme: Includes pingme. Useful for sending notifications to well-known services.
  • Note: pingme variants have fewer architectures. More architectures will be added in future.

All images contain:

• curl and jq, which are useful for sending notifications if needed
• rsync which is useful for incrementally copying mails or backups

Usage

Note: isync the project name, mbsync is the tool.

The mbsync config file used in this image is /mbsyncrc. The volume used to store local Maildir is /mail. The main sync script is /sync.

Here are three common sync cases:

• IMAP to Maildir - One-way sync of IMAP server to local Maildir
• Maildir to IMAP - One-way sync of local Maildir to IMAP server
• IMAP to IMAP - One-way sync of IMAP server to another IMAP server

For cron-based examples, see below.

For a simple demo of the three sync cases, see this docker-compose demo.

If needed, see official docs.

IMAP to Maildir

This syncs test@example.com to a local Maildir /mail. Sync state is kept in each folder in /mail.

Create config file mbsyncrc:

$ cat mbsyncrc
IMAPStore example-remote
Host imap.example.com
User test@example.com
Pass test
AuthMechs LOGIN
SSLType IMAPS
# Limit the number of simultaneous IMAP commands
PipelineDepth 30

MaildirStore example-local
SubFolders Verbatim
# The trailing '/' is important for Path
Path /mail/
Inbox /mail/INBOX

Channel example
Far :example-remote:
Near :example-local:
Patterns *
Create Near
Expunge Near
SyncState *
Sync Pull

Sync:

docker run --rm -it -v $(pwd)/mbsyncrc:/mbsyncrc:ro -v mail:/mail theohbrothers/docker-isync:latest

Maildir to IMAP

This syncs a local Maildir /mail to test2@example.com. Sync state is kept in each folder in /mail.

Create config file mbsyncrc:

$ cat mbsyncrc
IMAPStore example-remote-2
Host imap.example.com
User test2@example.com
Pass test
AuthMechs LOGIN
SSLType IMAPS
# Limit the number of simultaneous IMAP commands
PipelineDepth 30

MaildirStore example-local
SubFolders Verbatim
# The trailing '/' is important for Path
Path /mail/
Inbox /mail/INBOX

Channel example
Far :example-remote-2:
Near :example-local:
Patterns *
Create Far
Expunge Far
SyncState *
Sync Push

Sync:

docker run --rm -it -v $(pwd)/mbsyncrc:/mbsyncrc:ro -v mail:/mail theohbrothers/docker-isync:latest

IMAP to IMAP

This syncs test@example.com to test3@example.com. Sync state is kept in the /mbsync volume. The /mail volume is not used since there's no local Maildir.

Create config file mbsyncrc:

$ cat mbsyncrc
IMAPStore example-remote
Host imap.example.com
User test@example.com
Pass test
AuthMechs LOGIN
SSLType IMAPS
# Limit the number of simultaneous IMAP commands
PipelineDepth 30

IMAPStore example-remote-3
Host imap.example.com
User test3@example.com
Pass test
AuthMechs LOGIN
SSLType IMAPS
# Limit the number of simultaneous IMAP commands
PipelineDepth 30

Channel example
Far :example-remote:
Near :example-remote-3:
Patterns *
Create Near
Expunge Near
SyncState /mbsync/
Sync Pull

Sync:

docker run --rm -it -v $(pwd)/mbsyncrc:/mbsyncrc:ro -v mbsync:/mbsync theohbrothers/docker-isync:latest

Cron and notifications

For cron-based sync and backup with notifications, see docker-compose example(s):

• Cron-based sync with curl notifications
• Cron-based sync with pingme notifications
• Cron-based sync and backup (same container) with curl notifications
• Cron-based sync and backup (separate containers) with curl notifications

Secrets

Instead of typing secrets as plain text in /mbsyncrc config file for the User and Pass options of IMAPStore (or IMAPAccount), use UserCmd or PassCmd which accepts a shell command. This helps to separate configuration from secrets.

For example, if secrets are bind mounted as files in /run/secrets/user and /run/secrets/pass, use the following:

UserCmd "cat /run/secrets/user"
PassCmd "cat /run/secrets/pass"

If secrets are in environment variables IMAP_USER and IMAP_PASS, use the following:

UserCmd "echo $IMAP_USER"
PassCmd "echo $IMAP_PASS"

Command line usage

To view command line usage:

docker run --rm -it theohbrothers/docker-isync:latest --help

Known issues

• For Exchange servers or outlook.com IMAP servers, it might be necessary to use PipelineDepth 1 in the config file to limit the number of simultaneous IMAP commands. See here.

Development

Requires Windows powershell or pwsh.

# Install Generate-DockerImageVariants module: https://github.com/theohbrothers/Generate-DockerImageVariants
Install-Module -Name Generate-DockerImageVariants -Repository PSGallery -Scope CurrentUser -Force -Verbose

# Edit ./generate templates

# Generate the variants
Generate-DockerImageVariants .

Variant versions

versions.json contains a list of Semver versions, one per line.

To update versions in versions.json:

./Update-Versions.ps1

To update versions in versions.json, and open a PR for each changed version, and merge successful PRs one after another (to prevent merge conflicts), and finally create a tagged release and close milestone:

$env:GITHUB_TOKEN = 'xxx'
./Update-Versions.ps1 -PR -AutoMergeQueue -AutoRelease

To perform a dry run, use -WhatIf.