Is my domain set up for Microsoft 365?

What does that mean?

Setting a domain up for Microsoft 365 means two things. First, Microsoft has to know the domain is yours. For that you put a TXT record into DNS that starts with MS=ms. Second, the mail has to be delivered there. The MX record then points at a hostname ending in mail.protection.outlook.com.

On top of that comes the SPF record. It tells other mail servers who is allowed to send in your name. If include:spf.protection.outlook.com is missing from it, your messages land in recipients' spam folders more often.

The verification stays in place even when the mailboxes never moved. So its presence alone says nothing about whether Microsoft 365 is actually in use.

What can go wrong?

• Verification is in place, the MX record still points at the old provider. Then the mailboxes in Microsoft 365 stay empty.
• The MX record has been switched, SPF has not. Then your mail arrives, but your own messages look suspect to everyone else.
• Both are in place, but in two places: DNS at the registrar, MX at the host. Then whichever record actually gets published wins.
• Microsoft set the domain up automatically and overwrote the old records. An existing mailbox at the previous provider then takes nothing in.

How do you fix it?

All three records get set wherever your domain's nameservers point, not necessarily where the domain is registered. Which provider that is stands in the result above. The values themselves are given to you by the Microsoft 365 admin center under Settings and Domains.

Only switch the MX record once the mailboxes in Microsoft 365 exist. Between the switch and the first delivery there can be up to a day, depending on the lifetime of the old records.