We moved from Exchange 2010 on prem to Office 365 and we just cannot get the darn SMTP relay to take. I have followed dozens of write ups to the T, verified that the server could send on 25 / 587 by sending mail via powershell, and even hired two external vendors to look at this. No dice. I now have two questions that I need to get answers for:
- Is there somewhere in Office 365 where we can see the failed send, and why. NOTE: This is not the same as message trace.
- Does anyone know if the certificate needed for IIS to push TLS can be self signed or if has to be from a CA?
Thank you in advance,
-Ed