3

I redirect outgoing emails in my organization to my postfix MTA. from there, i'm redirecting the mails to office 365 for relaying to the original recipients.

For external recipients, I get the following error:

550 5.7.64 TenantAttribution; Relay Access Denied 
[....prod.protection.outlook.com] (in reply to RCPT TO command))

I have an inbound connector to 'Office 365' and still the mails are blocked with the error above.

danny h.
  • 31

2 Answers2

1

This suggests that you've not got a proper certificate chain set up on your local MTA. Have you reviewed article 3212877 in the Microsoft Knowedgebase? If you're using TLS (and you should) then the Exchange/O365 server needs to be able to validate all the certificates in any incoming TLS connection back to a trusted root.

Rob Moir
  • 32,154
0

I think you may first review your relay configuration on O365 according this official article.

And you could refer to this Microsoft KB article about this error. Please check the certificate on your postfix MTA, and the IP configuration about the connector.

Shaw Lu
  • 339