How to Migrate Email Accounts to Microsoft 365

How to Migrate Email Accounts to Microsoft 365

Migrating your email accounts to Microsoft 365 can feel overwhelming, especially if you’re concerned about losing emails, contacts, or calendar data. The good news is that with proper preparation and the right process, your migration can be completed safely with minimal downtime.

This guide walks you through how to migrate email accounts to Microsoft 365, explains what to expect at each stage, and highlights common pitfalls to avoid.

Steps to Complete the Migration

Step 1: Prepare Your Existing Email Environment

  1. Confirm usernames and passwords for all mailboxes to be migrated
  2. Gather current email server details (IMAP/POP server names and ports)
  3. Back up critical emails and data
Tip: If you’re unsure of your server settings, your current email provider can supply them.

Step 2: Set Up Your Microsoft 365 Admin Account

  1. Sign in to the Microsoft 365 Admin Center
  2. Confirm you have administrator permissions to create users and manage migrations
Admin access is required to run migrations and update DNS records.

Step 3: Create User Accounts in Microsoft 365

  • Create a Microsoft 365 user for each mailbox
  • Assign the appropriate license (for example, Microsoft 365 Business Standard)
Each mailbox must exist in Microsoft 365 before migration can begin.

Step 4: Gather Email Server Details

Collect the following for each mailbox:
  • IMAP server address
  • Port number
  • Username and password
  • SSL/TLS status (recommended)

Step 5: Upload the Mailbox List to the Migration Wizard

  1. Go to Admin Center > Exchange > Migration 
  2. Select IMAP migration
  3. Upload a CSV file containing mailbox details
The CSV typically includes:
  • Email address
  • Username
  • Password
  • IMAP server
This allows multiple mailboxes to be migrated in one batch.

Step 6: Start the Migration Batch

  • Review mailbox details carefully
  • Start the migration batch
Microsoft 365 will begin copying emails to the new mailboxes while users can continue working.

Step 7: Update DNS Records (Email Cutover)

Once mailboxes are syncing correctly:
  1. Log in to your DNS provider (e.g. GoDaddy or Namecheap)
  2. Update the following records:
    • MX (mail routing)
    • Autodiscover
    • SPF
Warning: Incorrect DNS changes can interrupt email delivery.

Step 8: Monitor Migration Progress

  • Track progress in the Exchange Admin Center
  • Large mailboxes may take several hours or run overnight

Step 9: Complete the Migration Batch

Once syncing is complete:
  • Select Complete Migration
  • Verify emails are present and accessible in Microsoft 365

Step 10: Decommission the Old Email Service (Optional)

After confirming all data has migrated successfully, deactivate the old email service if it’s no longer required.

If the Migration Fails

Basic Fixes to Try First

  • Double-check usernames and passwords if emails don’t appear
  • Restart Outlook or create a new Outlook profile
  • Allow time for DNS changes to fully propagate (30 minutes to several hours)

Advanced Fixes (Technical Users)

If you are not an administrator, contact your IT provider before making DNS or authentication changes.

  • Verify SSL/TLS port requirements; legacy servers may need manual configuration
  • Reduce batch sizes if throttling limits prevent migration of large mailboxes
  • Use Exchange Online PowerShell New-MigrationBatchfor bulk migrations
  • Run message trace in the Exchange Admin Center to identify missing emails
  • Clear Outlook autocomplete cache if old addresses continue to appear
  • Lower DNS TTL before cutover to speed up MX record propagation

Data Protection & Migration Warnings

  • Back up all data before starting the migration
  • Avoid large mailbox changes during migration
  • Expect short delays after DNS updates
  • Double-check credentials and server settings to prevent migration failures
  • Plan for large mailboxes, as migrations may take several hours
  • Reconfigure mobile devices after cutover if needed
  • Shared mailboxes need special setup to avoid access issues

Common Migration Questions

Will I lose emails during migration?
No. Emails are copied, not removed. Backups are still recommended.
Can I use my email while migrating?
Yes. Only the final cutover may cause brief delays.
How long does migration take?
Small accounts may take minutes, while large accounts can take several hours.
Do contacts and calendars migrate automatically?
No. IMAP migration transfers email only. Contacts and calendars must be migrated separately.
Can I migrate from Google Workspace or cPanel email?
Yes. Both can be migrated using IMAP, with separate steps for contacts and calendars.
Do I need to reinstall Outlook?
Usually not. Creating a new Outlook profile is sufficient.
Will my mobile devices continue to work?
Yes, but you may need to re-add accounts for proper syncing.
Do I need admin access?
Yes. Only a Microsoft 365 admin can run migrations and update DNS records.

Next Steps

Following this guide helps ensure a smooth, low-risk migration to Microsoft 365. However, complex environments, large mailboxes, or strict downtime requirements may benefit from professional assistance.

If you need expert support or want the migration handled end-to-end, Swazzy Support is available to help ensure everything is migrated correctly and securely.

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