Sending mail to Microsoft 365

Important

The improved Microsoft 365 security center is now available in public preview. This new experience brings Defender for Endpoint, Defender for Office 365, Microsoft 365 Defender, and more into the Microsoft 365 security center. Learn what's new. This topic might apply to both Microsoft Defender for Office 365 and Microsoft 365 Defender. Refer to the Applies To section and look for specific call-outs in this article where there might be differences.

These articles help external senders improve their reputation and increase their ability to deliver email to users in Microsoft 365. They also provide some information about how you can report junk email and phishing attempts even if you aren't a Microsoft 365 user yourself.

If you are not a customer, but are trying to send mail to someone in who is, you are in the right place. If you are an administrator and you need help fighting spam, this is not the right section for you. Instead, go to Anti-spam and anti-malware protection in Microsoft 365.


For information about... See...
Services we provide to administrators of email systems that are sending individual and bulk email to customers. Services for non-customers sending mail to Office 365
How to fix problems reaching customers in Microsoft 365 through email. Best practices for sending bulk mail to Microsoft 365 recipients. Troubleshooting mail sent to Office 365
How Microsoft 365 prevents junk email, including phishing and spoofing email, from being sent to our customers. Anti-spam protection in Microsoft 365
How you, an administrator sending email to Microsoft 365 customers, can avoid having email blocked by adhering to our anti-spam policies. This is the legal stuff you need to know. Reference: Policies, practices, and guidelines