Route Domain Email to Microsoft 365 with NicNames MX

Changing a domain's MX record sends new incoming mail to a different provider. Before pointing a NicNames domain to Microsoft 365, verify the domain, create every receiving mailbox, and plan the cutover. Then use the exact MX destination Microsoft shows for your organization and check delivery from outside it.

1. Prepare Microsoft 365 before moving mail

Add and verify your domain in the Microsoft 365 admin center first. Our NicNames TXT verification guide covers that separate ownership step. Create the Microsoft 365 users, shared mailboxes and addresses that must receive mail for the domain before changing MX. An MX change affects all new incoming mail addressed to the domain; it does not copy old messages or contacts from the previous provider. Arrange any mailbox migration and a cutover window with your mail administrator before proceeding.

In Microsoft 365, open Show all → Settings → Domains, select the verified domain, then open DNS records → Manage DNS. Choose manual setup if you manage your DNS records yourself. On the Add DNS records page, expand MX Records and copy the current host, destination and priority for your domain. Use the values shown for your organization, not a value copied from another domain's instructions.

2. Identify the DNS provider that serves your domain

In NicNames, open Domains → ClassicDNS, select the domain and read Name-Servers. Continue in the NicNames DNS editor only when Free Name-Servers are active. If Custom Name-Servers are active, make the MX change at the provider named by those servers. Switching nameservers just to enter an MX record can disrupt both website and email service.

Review the existing MX records and keep a copy of their exact values before the cutover. Identify which old records serve the provider you are leaving and whether any other mail-routing arrangement depends on them. An old MX record left alongside a new one can direct some mail to the wrong destination; do not treat it as an automatic backup.

3. Make the coordinated MX change

For a domain using NicNames Free Name-Servers, open DNS Records → Manage, select + Add record, and choose MX. For the root domain, leave Name empty. Enter Microsoft's current Priority and Mail server values into the matching fields; review TTL and keep it within Microsoft's supported range. Save only when the receiving Microsoft 365 mailboxes and your migration plan are ready. Coordinate removal of the old provider's conflicting root MX records as part of the same cutover.

Do not change the website's A, AAAA or CNAME records merely to move mail. Microsoft may show other DNS records for service discovery or email authentication; review those separately using its current setup wizard. When you are ready to enable signing, our Microsoft 365 DKIM guide for NicNames DNS covers the two tenant-specific CNAME records.

4. Verify delivery and handle a mismatch

Return to the Microsoft 365 domain setup page and check its DNS status. Confirm that public MX lookups show the destination and priority you entered, then send a test message from an address outside your Microsoft 365 organization to each important receiving address. Check the Microsoft 365 inboxes and your mail administrator's delivery diagnostics. During the transition, monitor the old mail system until cached MX answers have aged out; do not shut it down solely because one test succeeded.

If Microsoft reports a missing record or messages still arrive at the old provider, compare the active nameservers, root hostname, priority and mail-server value with Microsoft's current setup page. Our DNS change troubleshooting checklist explains authoritative and cached answers. If the NicNames editor rejects a value or the active zone remains unclear, contact NicNames Support with the domain and record details, without sending passwords or private tokens.