imapsync-go

imapsync-go is a lightweight Go CLI that mirrors folders between two IMAP accounts. It builds a sync plan from message IDs, streams mail bodies directly between servers.

Note: This project was created in collaboration with the GPT 5.1 Codex agent model.

Motivation

This tool was built to provide a simple, fast, and dependency-free solution for IMAP synchronization. Key goals:

• Zero dependencies - Single static binary with no external requirements
• Cross-platform - Works on Linux and macOS (amd64/arm64)
• Efficient - Parallel workers for fast synchronization
• Simple - Easy configuration via JSON or YAML

Unlike heavyweight alternatives, imapsync-go focuses on doing one thing well: efficiently copying IMAP folders between servers.

Installation

Homebrew (macOS)

brew tap greeddj/tap
brew install imapsync-go

Docker

Pull the image from GitHub Container Registry:

# Latest version
podman pull ghcr.io/greeddj/imapsync-go:latest
# or
podman pull ghcr.io/greeddj/imapsync-go:1.0.0

Binary Release

Download pre-built binaries from GitHub Releases:

# Example for Linux amd64
curl -LO https://github.com/greeddj/imapsync-go/releases/latest/download/imapsync-go_<version>_Linux_x86_64.tar.gz
tar xzf imapsync-go_<version>_Linux_x86_64.tar.gz
chmod +x imapsync-go
sudo mv imapsync-go /usr/local/bin/
sudo xattr -rd com.apple.quarantine /usr/local/bin/imapsync-go

Usage

Configuration

Create a configuration file (config.json or config.yaml):

JSON example:

{
  "src": {
    "label": "Source",
    "server": "imap.source.com:993",
    "user": "user@source.com",
    "pass": "password"
  },
  "dst": {
    "label": "Destination",
    "server": "imap.dest.com:993",
    "user": "user@dest.com",
    "pass": "password"
  },
  "map": [
    {"src": "INBOX", "dst": "INBOX"},
    {"src": "Sent", "dst": "Sent Items"}
  ]
}

YAML example:

src:
  label: Source
  server: imap.source.com:993
  user: user@source.com
  pass: password

dst:
  label: Destination
  server: imap.dest.com:993
  user: user@dest.com
  pass: password

map:
  - src: INBOX
    dst: INBOX
  - src: Sent
    dst: Sent Items

Running with Homebrew

export IMAPSYNC_CONFIG="/Users/$(whoami)/.imapsync/prod_config.json"

# Show available folders
imapsync-go show

# Sync all configured folders
imapsync-go sync -w 4

# Sync specific folder
imapsync-go sync -s INBOX -d INBOX
imapsync-go sync -s 'Test.[some_group].box' -d 'Test/some_group/box'

# Auto-confirm without prompt
imapsync-go sync -y

Running with Docker

# show folders
podman run --rm \
-v /Users/$(whoami)/.imapsync/prod_config.json:/config.json ghcr.io/greeddj/imapsync-go:latest \
-c /config.json \
show

# sync folders
podman run --rm -it \
-v /Users/$(whoami)/.imapsync/prod_config.json:/config.json ghcr.io/greeddj/imapsync-go:latest \
-c /config.json \
sync -w 4

Command-line Options

Global flags:

• -c, --config - Path to configuration file (default: config.json)

Sync command:

• -s, --src-folder - Source folder (overrides config)
• -d, --dest-folder - Destination folder (overrides config)
• -w, --workers - Number of parallel workers (default: 4, max: 10)
• -y, --confirm - Auto-confirm without prompt
• -V, --verbose - Enable verbose output
• -q, --quiet - Suppress non-error output

Show command:

• -V, --verbose - Enable verbose output

License

MIT