How to Migrate Email Services to a New Server

Email migration requires careful planning to avoid downtime and lost messages. This guide covers moving your mail services between Breeze instances with minimal disruption.

Pre-Migration Checklist

• Document current mail server software (Postfix, Dovecot, etc.) and versions
• Export all mailbox accounts and aliases
• Record DNS records: MX, SPF, DKIM, and DMARC
• Lower your MX record TTL to 300 seconds several days before migration

Step 1: Set Up the New Mail Server

sudo apt install -y postfix dovecot-imapd dovecot-pop3d
sudo systemctl enable postfix dovecot

Replicate your configuration files from the old server, adjusting hostnames and paths as needed.

Step 2: Sync Mailboxes

Use imapsync to transfer all messages between servers:

imapsync --host1 old.example.com --user1 user@example.com --password1 "oldpass" \
         --host2 new.example.com --user2 user@example.com --password2 "newpass" \
         --ssl1 --ssl2

Step 3: Update DNS Records

Point MX records to the new server IP:

example.com.  300  IN  MX  10  mail.example.com.
mail.example.com.  300  IN  A  203.0.113.50

Update SPF and DKIM records to reference the new server.

Step 4: Verify Delivery

echo "Test email" | mail -s "Migration test" user@example.com
sudo tail -f /var/log/mail.log

Post-Migration

• Run imapsync a second time to catch messages that arrived during DNS propagation
• Monitor both servers for 48 hours before decommissioning the old one
• Restore MX TTL to its normal value once migration is confirmed