Zero-Downtime Email Migration

4 min read

Migrating email is trickier than migrating a website. If you just flip the MX records, you’ll lose emails sent during propagation (some servers deliver to the old host, some to the new). The steps below move your mail across without losing a message.

The Problem link

When you change MX records, DNS propagation takes up to 48 hours. During that window:

• Some senders’ DNS caches still point to the old mail server
• Other senders see the new MX records and deliver to GoZen
• Emails sent to the old server during propagation can be lost if you’ve already cancelled that account

The Zero-Downtime Process link

Phase 1: Set Up Email Accounts on GoZen (Before Changing Anything) link

1. Log into cPanel on your GoZen Host account
2. Go to Email > Email Accounts
3. Create every email account that exists on your old host, using the same addresses
4. Set passwords for each account

Don’t change DNS yet. Just create the accounts.

Phase 2: Sync Existing Emails link

Transfer your existing emails from the old host to GoZen so you have a complete history:

Option A: IMAP Sync with imapsync (fastest for large mailboxes)

imapsync runs from any computer that can reach both mail servers, including your own. You don’t need shell access on either host.

  imapsync \
  --host1 old-mail-server.com --user1 [email protected] --password1 "oldpassword" \
  --host2 your-server-hostname --user2 [email protected] --password2 "newpassword" \
  --ssl1 --ssl2
  

Replace your-server-hostname with your GoZen server’s hostname, found in cPanel > Email Accounts > Connect Devices. Don’t use mail.yourdomain.com here: until you change DNS it still points at your old host, and imapsync would copy the old mailbox onto itself.

This copies all folders, messages, and flags from the old server to GoZen.

Option B: Email Client Drag-and-Drop

1. Add both email accounts to Thunderbird or Outlook. For the GoZen account, use your server hostname from cPanel > Email Accounts > Connect Devices as the IMAP server, not mail.yourdomain.com, which still points at the old host
2. Select all messages in each folder on the old account
3. Drag them to the corresponding folder on the GoZen account
4. Wait for the sync to complete

Option C: Contact Support

Open a support ticket and we’ll handle the migration. Include your old server’s IMAP details.

Phase 3: Change MX Records link

Now that accounts are created and emails are synced, point your MX records to GoZen:

1. A day before the switch, lower the TTL on your MX records to 300 seconds without changing their values, so the switch takes minutes rather than hours
2. Go to your domain registrar’s DNS management
3. Update the MX records to GoZen’s mail servers (check your welcome email for the exact values)
4. At the same time, add GoZen’s server to your SPF record. cPanel > Email > Email Deliverability shows the GoZen entries to use. Edit the existing record rather than adding a second one, and keep the old host’s entries in it: your mail clients still send through the old host until you move them in Phase 5. Without the GoZen entries, mail sent from GoZen can land in spam
5. Keep the old email account active during this phase

Phase 4: Dual Delivery Period link

For the next 48 hours, emails might arrive at either server. To catch everything:

1. Keep the old email account active and check it periodically
2. Don’t set up forwarding on the old host. The old server still treats your domain as local, so a forward to the same address is delivered back into the old mailbox. The final sync in Phase 5 brings these messages across
3. Monitor both inboxes for 48 hours

Phase 5: Clean Up link

After 48 hours:

1. Verify that all new emails arrive at GoZen (check your GoZen webmail)
2. Run the Phase 2 sync again to catch any stragglers. imapsync skips messages it already copied, so only new ones transfer
3. Update your email client to point to GoZen’s mail server
4. Once every client sends through GoZen, remove the old host’s entries from your SPF record
5. Cancel the old hosting account (only after confirming everything works)

Updating Email Clients link

After migration, update your email clients (Outlook, Thunderbird, mobile) to use GoZen’s server:

See Gmail Setup and Outlook Setup for step-by-step guides.

Email Authentication link

After the MX records point to GoZen, check that SPF, DKIM, and DMARC are in place to keep your emails out of spam folders:

1. In cPanel, go to Email > Email Deliverability
2. Click Repair next to your domain if there are warnings
3. Verify at GoZen DNS Inspector

See Email Delivery Problems for full setup details.

What to Do Next link

• Setting Up Email Accounts in cPanel - configure your email accounts
• Email Delivery Problems - fix deliverability after migration
• Set Up GoZen Email in Gmail - access your new email from Gmail
• Want us to do the whole move? - GoZen offers free migration on every plan, mailboxes and websites included