Email Migration

How to Migrate Email from a Third-Party Host to Microsoft 365

WPS Content Manager Oct 10, 2026 869 views

Question details

The user needs to move their business email accounts and existing message data from a third-party website host to Microsoft 365.

How to Migrate Email from a Third-Party Host to Microsoft 365

Product: Microsoft 365
Device & OS: not provided
Scenario: Migrating a company's email infrastructure to Microsoft 365 from another hosting provider (such as GIACOM or a standard web host).
Observed behavior: The goal is to successfully transfer existing messages and contacts, verify the domain, and establish correct mail flow using updated DNS records.

Before you start

Ensure you have administrator credentials for your Microsoft 365 admin center, access to your old email provider's portal, and login details for your domain registrar's DNS settings.

Solution 1Recommended

Perform a Manual Email Migration and Update DNS Records

This comprehensive process covers preparing your new mailboxes, migrating your existing data, and updating your domain's DNS records to route mail to Microsoft 365.

Moving to Microsoft 365 requires carefully transferring your old emails before pointing your domain's email traffic to Microsoft's servers. This prevents data loss and minimizes downtime.

Create Microsoft 365 Mailboxes

Log in to the Microsoft 365 admin center, navigate to Users > Active users, and add your team members to generate their new, empty mailboxes.

Export and Migrate Data

Export your existing emails and contacts from the third-party host (via PST files or an IMAP migration batch in the Exchange admin center) and sync them to the newly created Microsoft 365 mailboxes.

Verify Your Domain

In the Microsoft 365 admin center, go to Settings > Domains. Choose 'Add domain', enter your custom domain name, and verify ownership by adding the provided TXT record to your domain's DNS host.

Update DNS Records

Access your domain registrar's DNS management portal. Update the MX record to route new mail to Microsoft, add the Autodiscover CNAME record, and configure your SPF (TXT) record for security. Add DKIM and DMARC records as applicable.

Test Mail Flow

Once DNS changes are saved, send test emails to and from the newly configured Microsoft 365 accounts to ensure inbound and outbound routing is functioning properly.

Perform a Manual Email Migration and Update DNS Records

DNS Propagation Time: It may take up to 48 hours for DNS changes to fully propagate globally. Keep your previous third-party host active until mail flow is fully confirmed.

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Frequently Asked Questions

What DNS records need to be updated for Microsoft 365 email?

You primarily need to update the MX record for mail routing, the TXT (SPF) record for email authentication to prevent spam, and CNAME records (like Autodiscover) to connect email clients automatically.

Will my emails be lost during the domain migration?

No, as long as you perform the data migration (via IMAP or PST import) before changing the MX records, and keep the old host active until DNS propagation is complete, no emails will be lost.

Can I migrate contacts and calendars using an IMAP migration?

No, IMAP migrations only transfer email messages. To migrate contacts and calendars, you must export them from your previous host (often as PST or CSV files) and import them manually, or use a specialized third-party migration tool.

How long does it take for the new email settings to take effect?

While creating mailboxes and starting a migration batch can be relatively quick, DNS record changes (especially MX records) can take anywhere from 1 to 48 hours to fully propagate across the internet.

Migration & Recovery