• Estimated time to complete: 5 minutes
  
  
• You need to be assigned permissions before you can perform this procedure or procedures. To see what permissions you need, see the "Accepted domains" entry in the Mail Flow Permissions topic.
  
  
• You can't create an accepted domain that has the same name as an already configured remote domain. For example, if you have fabrikam.com configured as a remote domain, you can't create an accepted domain for fabrikam.com.
  
  
• Before you configure an accepted domain, you must verify that a public Domain Name System (DNS) MX resource record for that SMTP namespace exists and that the MX resource record references a server name and an IP address associated with your Exchange organization.
  
  
• For information about keyboard shortcuts that may apply to the procedures in this topic, see Keyboard Shortcuts in the Exchange Admin Center.
  
  

Tip:
Having problems? Ask for help in the Exchange forums. Visit the forums at: Exchange Server, Exchange Online, or Exchange Online Protection

If an accepted domain for your Exchange organization hosts all the mailboxes for recipients within that domain’s SMTP namespace, you may want to configure it as an authoritative domain.

1. In the EAC, navigate to Mail flow > Accepted domains, and click Add .
   
   
2. In the Name field, enter the display name for the accepted domain. Each accepted domain for your organization must have a unique display name This may be different than the accepted domain. For example, the domain contoso.com could have a display name of Contoso Local Accepted Domain.
   
   
3. In the Accepted domain field, enter the accepted domain. Specify an SMTP namespace for which your organization accepts email messages. (for example, Contoso.com).
   
   
4. Select Authoritative domain. This option is for email relayed to servers within your Exchange organization for an accepted domain that hosts mailboxes for all the recipients within an SMTP namespace.
   
   
5. Click Save.
   
   

Tip:
To configure an accepted domain that has already been created, select the domain from the accepted domains list and click Edit . You can configure more than one domain as authoritative.

Your new accepted domain will appear in the accepted domains list in the EAC. To verify that you have successfully configured the accepted domain as authoritative, send mail to the domain and verify that it is received.