Migrating Email to a New Provider

Overview

Migrating email to a new provider involves moving your mailboxes, messages, contacts, and calendar data while ensuring uninterrupted email delivery during the transition. Careful planning is essential to avoid lost messages or downtime.

Pre-Migration Checklist

Before you begin the migration:

• Document current settings — Record your existing mail server hostnames, ports, DNS records (MX, SPF, DKIM, DMARC), and user accounts.
• Back up all email — Download a full backup of all mailboxes. Most email clients can export to PST (Outlook), MBOX, or EML format.
• Inventory accounts — List every mailbox, alias, forwarding rule, and distribution list that needs to be recreated.
• Lower MX record TTL — At least 24–48 hours before migration, reduce the TTL on your MX records to 300–600 seconds. This allows you to switch mail routing quickly.
• Inform users — Let all email users know about the migration timeline and any expected downtime.

Step 1: Set Up the New Provider

1. Create your account with the new email provider.
2. Add and verify your domain.
3. Recreate all mailboxes, aliases, and distribution lists with the same addresses.
4. Configure SPF, DKIM, and DMARC records as required by the new provider (but do not activate them yet).

Step 2: Migrate Email Data

Option A: IMAP Migration

Most providers support IMAP-to-IMAP migration. You can use:

• Email client (Thunderbird) — Add both the old and new accounts, then drag and drop folders from old to new.
• imapsync — A command-line tool that synchronizes mailboxes between two IMAP servers. Ideal for bulk migrations.
• Provider migration tools — Google Workspace and Microsoft 365 have built-in data migration tools in their admin consoles.

Option B: PST/MBOX Import

1. Export mail from the old provider to PST (Outlook) or MBOX format.
2. Import the files into the new provider using their import tool or an email client.

Option C: Third-Party Migration Tools

Services like BitTitan MigrationWiz or CloudMigrator can handle large-scale migrations between most email platforms with minimal configuration.

Step 3: Switch MX Records

Once mailboxes are set up and data migration is underway or complete:

1. Log in to your 10Corp domain dashboard.
2. Navigate to DNS Management.
3. Replace the old MX records with the new provider’s MX records.
4. Update the SPF record to reflect the new provider’s sending servers.
5. Activate DKIM signing at the new provider.
6. Update or add your DMARC record.

Step 4: Post-Migration Verification

• Send test emails to and from the new mailboxes using external addresses.
• Verify MX records have propagated using MXToolbox or nslookup -type=MX yourdomain.com.
• Check SPF, DKIM, and DMARC using mail-tester.com.
• Monitor for bounces during the first 48 hours.
• Configure email clients on all devices with the new server settings.

Step 5: Decommission Old Service

• Keep the old email service active for at least one week after switching MX records to catch any messages routed via cached DNS entries.
• Perform a final sync or data export to ensure no messages were missed.
• Cancel the old service once you are confident the migration is complete.

Tips

• Schedule the migration during off-peak hours or over a weekend to minimize disruption.
• Use a coexistence period where both old and new services are active.
• Remind users to update passwords and reconfigure mobile devices after migration.