🛠 FULL EMAIL MIGRATION PROCESS

Step 0: Preparation

  1. SSH access to both servers (OLD and NEW).
  2. Make sure both Mailcow servers are running.
  3. Verify the domain and mailboxes already exist on the new server.
  4. Optional but recommended: backup the new server’s mailbox folder:

 

cp -r /opt/mailcow-dockerized/data/vmail/ampnetwork.com.np /opt/mailcow-dockerized/data/vmail/ampnetwork.com.np.bak

Step 1: Stop incoming mail temporarily (optional but safer)

  • On OLD server, you can stop postfix/dovecot temporarily to avoid new emails arriving during migration:

 

docker compose stop postfix-mailcow dovecot-mailcow

  • On NEW server, it’s okay to keep services running.

Step 2: Copy mailbox data from OLD → NEW server

Use rsync to transfer emails. On OLD server:


 

rsync -avz --progress /opt/mailcow-dockerized/data/vmail/ampnetwork.com.np/ user@NEW_SERVER_IP:/opt/mailcow-dockerized/data/vmail/ampnetwork.com.np/

Notes:

  • user@NEW_SERVER_IP → replace with your SSH user and IP of new server.
  • Trailing slash / at the end of source ensures only the contents of the domain folder are copied, not the folder itself.
  • --progress shows transfer progress; add --partial --bwlimit=1000 for very large mailboxes to limit bandwidth.

Step 3: Fix permissions on NEW server

After transfer, on the NEW server, make sure Dovecot can read the emails:


 

docker compose exec dovecot-mailcow chown -R vmail:vmail /var/vmail/ampnetwork.com.np

Step 4: Reindex / resync mailboxes

Now tell Dovecot to scan and register all emails. You can:

Option A: Resync all mailboxes of the domain:


 

docker compose exec dovecot-mailcow doveadm force-resync -u info@ampnetwork.com.np '*'

Repeat this command for each mailbox if you have multiple users.

Option B: Resync all mailboxes (if only this domain exists):


 

docker compose exec dovecot-mailcow doveadm force-resync -A '*'

Step 5: Verify the migration

  1. Log in via webmail or IMAP client (Thunderbird, Outlook).
  2. Check:
    • All folders are present (Inbox, Sent, Drafts, Trash)
    • Emails are correctly migrated
    • No duplicates unless previously existed

Step 6: Resume mail flow

  • If you stopped postfix/dovecot on OLD server, restart:

 

docker compose start postfix-mailcow dovecot-mailcow

Optional: Clean up old server mail

  • Once you confirm emails are fully migrated and working on NEW server, you can optionally remove old vmail data to free space:

 

rm -rf /opt/mailcow-dockerized/data/vmail/ampnetwork.com.np

✅ Notes & Best Practices

  1. Use rsync over SSH → ensures safe transfer and resume if interrupted.
  2. Keep backups → especially before deleting anything.
  3. Permissions matter → Dovecot won’t see emails if ownership is wrong.
  4. Large mailboxes → consider transferring at night or in batches using mailbox subfolders.

This method migrates only the selected domain’s emails, keeps mailbox structure intact, and works for any number of mailboxes.

 

#!/bin/bash
# =========================================
# Mailcow domain migration script
# Migrates all mailboxes of ampnetwork.com.np
# =========================================

# =========================
# CONFIGURATION - EDIT THESE
# =========================
OLD_SERVER="old.server.ip.or.hostname"
OLD_USER="ssh_user_on_old"
NEW_SERVER="new.server.ip.or.hostname"   # usually localhost if running on new server
DOMAIN="ampnetwork.com.np"
VMAIL_PATH="/opt/mailcow-dockerized/data/vmail"
MAILCOW_PATH="/opt/mailcow-dockerized"

# =========================
# 1️⃣ Backup existing vmail on NEW server (optional but recommended)
# =========================
echo "Backing up current vmail data on NEW server..."
ssh $NEW_SERVER "cp -r $VMAIL_PATH/$DOMAIN ${VMAIL_PATH}/${DOMAIN}.bak_$(date +%Y%m%d%H%M%S)"

# =========================
# 2️⃣ Sync emails from OLD to NEW server
# =========================
echo "Syncing emails from OLD to NEW server..."
rsync -avz --progress $OLD_USER@$OLD_SERVER:$VMAIL_PATH/$DOMAIN/ $VMAIL_PATH/$DOMAIN/

# =========================
# 3️⃣ Fix permissions on NEW server
# =========================
echo "Fixing permissions on NEW server..."
ssh $NEW_SERVER "docker compose -f $MAILCOW_PATH/docker-compose.yml exec dovecot-mailcow chown -R vmail:vmail /var/vmail/$DOMAIN"

# =========================
# 4️⃣ Resync mailboxes on NEW server
# =========================
echo "Resyncing mailboxes on NEW server..."
ssh $NEW_SERVER "docker compose -f $MAILCOW_PATH/docker-compose.yml exec dovecot-mailcow doveadm force-resync -A '*'"

echo "Migration completed successfully for domain $DOMAIN!"