Add this CNAME at your DNS host: name = autodiscover, target = autodiscover.outlook.com. Full record: autodiscover.yourdomain.com. CNAME autodiscover.outlook.com.. This lets Outlook clients (desktop and mobile) automatically find your Microsoft 365 mail configuration when someone enters just their email address. Do NOT combine Autodiscover CNAME with an SRV record for the same purpose; pick one method. Verify with the DNS query tool. After the CNAME propagates, Outlook autodiscover should resolve mailbox settings automatically for new clients.
All questions
How do I add a CNAME for Office 365 Autodiscover?
Read the full guide
What Is DKIM?
DKIM attaches a cryptographic signature to every email you send. Receiving servers verify the signature against a public key in your DNS — proving the message is authentic and untampered. No DKIM means anyone can forge your brand's email.