550 5.7.64 Relay Access Denied ATTR36

Copper Contributor

Dear Sir,


We are seeing SMTP ; 550 5.7.64 TenantAttribution; Relay Access Denied [OS2JPN01FT010.eop-JPN01.prod.protection.outlook.com]. while sending emails from relay using (Java program) tomcat server.


Thank you



2 Replies

Literally the first result in search: https://docs.microsoft.com/en-us/exchange/troubleshoot/connectors/relay-access-denied-smtp


As detailed in the article, to relay messages via O365, you need a connector, verified either by a certificate or restricted to specific IP address.