How to Migrate Email to Microsoft 365

Overview

Migrating email to Microsoft 365 is one of the most common projects for businesses moving to the cloud. The process varies depending on your current email provider, but Microsoft provides built-in tools that handle most of the heavy lifting.

This guide covers the three main migration methods, when to use each, and the critical DNS and security steps after migration.

Which Migration Method Should You Use?

Pre-Migration Checklist

Before starting any migration:

1. Verify licences — every user needs a Microsoft 365 licence with Exchange Online
2. Add your domain to Microsoft 365 (admin.microsoft.com > Settings > Domains)
3. Verify the domain via DNS TXT record
4. Create user accounts in Microsoft 365 (or sync from AD via Entra Connect)
5. Document current settings — distribution lists, aliases, forwarding rules, shared mailboxes
6. Communicate to users — set expectations for downtime and what they need to do

Method 1: IMAP Migration (Most Common)

Works with any email provider that supports IMAP: GoDaddy, Rackspace, Zoho, Hostinger, cPanel, etc.

What migrates

• Email messages and folders
• Read/unread status

What does NOT migrate

• Contacts and calendars (must be exported/imported separately)
• Email rules and signatures
• Sent items (on some IMAP servers)

Step 1 — Verify IMAP access with your current provider

You need the IMAP server address and port:

Step 2 — Create a migration CSV file

Create a CSV with every mailbox to migrate:

EmailAddress,UserName,Password
[email protected],[email protected],OldPassword1
[email protected],[email protected],OldPassword2

Step 3 — Run the migration in Exchange admin center

1. Go to admin.exchange.microsoft.com > Migration
2. Click Add migration batch
3. Select Migration to Exchange Online > IMAP migration
4. Upload your CSV file
5. Enter the IMAP server address and port (993, SSL)
6. Set the batch name and start the migration

Step 4 — Monitor progress

The migration dashboard shows per-mailbox status. Large mailboxes (10GB+) can take several hours.

Step 5 — Switch MX records

Once all mailboxes show "Synced", update your DNS:

1. Change your MX record to point to Microsoft 365:
   • Priority: 0
   • Host: @
   • Points to: yourdomain-com.mail.protection.outlook.com
2. Wait for DNS propagation (up to 48 hours, usually 1-4 hours)
3. Verify mail flow by sending test emails

Step 6 — Complete the migration

After verifying mail flow works correctly:

1. Go back to the migration batch in Exchange admin center
2. Click Complete to finalise the batch
3. This stops syncing from the old server

Method 2: Google Workspace Migration

Microsoft has a dedicated tool for migrating from Google Workspace.

Step 1 — Grant migration access

1. In Google Admin Console, create a service account with domain-wide delegation
2. Grant the following API scopes:
   • https://mail.google.com/
   • https://www.googleapis.com/auth/calendar
   • https://www.googleapis.com/auth/contacts

Step 2 — Run the migration

1. Go to admin.microsoft.com > Setup > Data migration
2. Select Gmail as the source
3. Enter the Google Workspace service account credentials
4. Select which users to migrate
5. Choose what to migrate: Email, Contacts, Calendar (all three recommended)
6. Start the migration

Method 3: Cutover Migration (from Exchange Server)

For organisations running on-premises Exchange Server with fewer than 150 mailboxes.

What migrates

• All email, contacts, and calendar items
• Distribution groups
• Mailbox permissions

Step 1 — Configure Outlook Anywhere

Ensure Outlook Anywhere (RPC over HTTP) is enabled on your on-premises Exchange server.

Step 2 — Run the migration

1. Go to admin.exchange.microsoft.com > Migration
2. Click Add migration batch > Migration to Exchange Online > Cutover migration
3. Enter your on-premises Exchange server details
4. Microsoft 365 will discover all mailboxes automatically
5. Start the migration

Step 3 — Verify and switch MX

Same process as IMAP migration — verify all mailboxes are synced, then update MX records.

Post-Migration Steps (Critical)

1. Update DNS records

After switching MX, also configure:

See our full SPF/DKIM/DMARC guide for detailed setup.

2. Recreate distribution groups and aliases

IMAP and Google migrations do not migrate distribution lists. Recreate them in Exchange admin center or via PowerShell:

# Create a distribution group
New-DistributionGroup -Name "Sales Team" -Alias "sales" -PrimarySmtpAddress "[email protected]"
Add-DistributionGroupMember -Identity "Sales Team" -Member "[email protected]"

3. Set up shared mailboxes

# Create a shared mailbox
New-Mailbox -Shared -Name "Support" -PrimarySmtpAddress "[email protected]"
Add-MailboxPermission -Identity "[email protected]" -User "[email protected]" -AccessRights FullAccess

4. Configure Outlook on user devices

After MX switch, users may need to:

• Create a new Outlook profile (recommended for cleanest setup)
• Or clear cached credentials and restart Outlook

See our Outlook troubleshooting guide if users have connectivity issues.

5. Enable security features

Now that email is on Microsoft 365, enable:

• MFA for all users — MFA setup guide
• Conditional Access — CA guide
• Microsoft Defender for Office 365 — Safe Links, Safe Attachments, anti-phishing policies
• Audit logging — enabled by default, verify in Purview compliance portal

6. Decommission the old email server

Wait at least 30 days after migration before decommissioning the old server:

1. Verify no email is still routing to the old server
2. Export any remaining data (archives, public folders)
3. Cancel the old email hosting subscription
4. Remove old DNS records that pointed to the previous server

Troubleshooting