WkMailSync

Mail synchronization and backup tool in Go. Syncs IMAP→IMAP, IMAP→EML, Maildir→EML/Zip, or bulk-exports all users from a Virtualmin server.

Features

• IMAP→IMAP sync with deduplication
• IMAP→EML or IMAP→Zip export
• Local Maildir as source
• Virtualmin integration — enumerate domains/users via local CLI, SSH, or HTTP API
• Zip output — one archive per user
• Date range filtering
• Subdirectory organization with auto-detected IMAP separator
• Dry-run mode
• Charset fallback, malformed MIME handling, auto-reconnect

Build

git clone https://github.com/Warky-Devs/WkMailSync.git
cd WkMailSync
go build ./cmd/WKMailSync

Requires Go 1.24+.

Quick Start

# IMAP → IMAP
./WKMailSync -src-host src.example.com -src-user u@src.com -src-pass p1 \
             -dest-host dst.example.com -dest-user u@dst.com -dest-pass p2

# IMAP → EML files
./WKMailSync -src-host src.example.com -src-user u@src.com -src-pass p1 \
             -output-dir /backup/mail

# IMAP → Zip
./WKMailSync -src-host src.example.com -src-user u@src.com -src-pass p1 \
             -output-dir /backup -output-format zip

# Maildir → EML files
./WKMailSync -config maildir.yaml

# Maildir → Zip
./WKMailSync -config maildir-zip.yaml

# Config file
./WKMailSync -config config.yaml

Maildir examples

maildir.yaml — export a local Maildir to EML files:

maildir_source:
  path: "/home/user/Maildir"
  user: "user"
  domain: "example.com"

output_dir: "/backup/mail"
dry_run: false

maildir-zip.yaml — same but compressed:

maildir_source:
  path: "/home/user/Maildir"
  user: "user"
  domain: "example.com"

output_dir: "/backup"
output_format: "zip"

Date filtering works with Maildir too:

maildir_source:
  path: "/home/user/Maildir"

output_dir: "/backup/mail"
date_from: "2024-01-01"
date_to: "2024-12-31"

Config File

source:
  host: "mail.example.com"
  port: "993"
  username: "user@example.com"
  password: "secret"
  use_tls: true
  insecure_tls: false

# IMAP destination (optional — omit if using output_dir)
destination:
  host: "mail2.example.com"
  port: "993"
  username: "user@example.com"
  password: "secret"
  use_tls: true

output_dir: "/backup/mail"   # omit for IMAP destination
output_format: "eml"         # eml (default) | zip
subdirectory: ""             # e.g. "Archive" → Archive/INBOX, Archive/Sent
date_from: "2024-01-01"      # optional
date_to: "2024-12-31"        # optional
dry_run: false

Maildir Source

Read directly from a local Maildir directory instead of IMAP:

maildir_source:
  path: "/home/user/Maildir"
  domain: "example.com"
  user: "user"

output_dir: "/backup/mail"
output_format: "zip"

Virtualmin Integration

Enumerate all domains and users, then sync each user's Maildir.

Local (run on the Virtualmin server itself):

virtualmin:
  mode: "local"
  domain: ""             # optional: filter to one domain
  maildir_base: ""       # optional: default /home/%s/homes/%s/Maildir

output_dir: "/backup/mail"
output_format: "zip"

SSH (run remotely):

virtualmin:
  mode: "ssh"
  ssh:
    host: "server.example.com"
    port: "22"
    username: "root"
    key_file: "/home/user/.ssh/id_rsa"
    # password: "secret"   # alternative to key_file

output_dir: "/backup/mail"
output_format: "zip"

API (Webmin HTTP API):

virtualmin:
  mode: "api"
  api:
    host: "server.example.com"
    port: "10000"
    username: "admin"
    password: "secret"
    use_tls: true
    insecure_tls: false
    ssh:                          # for reading mail over SFTP
      host: "server.example.com"
      username: "root"
      key_file: "/home/user/.ssh/id_rsa"

output_dir: "/backup/mail"
output_format: "zip"

CLI Flags

Flag	Default	Description
-config		YAML config file
-src-host		Source IMAP host
-src-port	993	Source IMAP port
-src-user		Source username
-src-pass		Source password
-src-tls	true	TLS for source
-src-insecure	false	Skip cert verification
-dest-host		Destination IMAP host
-dest-port	993	Destination IMAP port
-dest-user		Destination username
-dest-pass		Destination password
-dest-tls	true	TLS for destination
-dest-insecure	false	Skip cert verification
-output-dir		Output directory (EML/Zip)
-output-format	eml	eml or zip
-subdirectory		Destination subdirectory prefix
-date-from		Sync messages from date
-date-to		Sync messages up to date
-dry-run	false	Preview without changes

Date Formats

YYYY-MM-DD · YYYY-MM-DDTHH:MM:SS · YYYY-MM-DD HH:MM:SS · RFC3339

Output Structure

EML: output_dir/FolderName/YYYYMMDD_HHMMSS_Subject_From.eml

Zip: output_dir/username_YYYYMMDD_HHMMSS.zip with FolderName/YYYYMMDD_HHMMSS_Subject_From.eml inside

Package Structure

cmd/WKMailSync/main.go     — CLI entry point
pkg/config/                — Config structs + YAML loading
pkg/source/                — MailSource interface, IMAP + Maildir implementations
pkg/output/                — MailOutput interface, EML + Zip + IMAP implementations
pkg/sync/                  — SyncEngine (source → output, filtering, dedup, stats)
pkg/connector/             — VirtualminConnector interface, local/SSH/API implementations

Troubleshooting

Connection refused / TLS error — check host, port, use_tls, try insecure_tls: true for self-signed certs.

Malformed MIME / charset errors — handled automatically with raw fallback copy.

Virtualmin CLI not found — local mode requires virtualmin binary in PATH on the target machine.

License

MIT