@Mike-Davis said in Troubleshooting Postfix Authentication to Relay:

@jt1001001 said in Troubleshooting Postfix Authentication to Relay:

is there some sort of anti-spoofing settings with Intermedia?

That's probably what is going on. I was working with their support last night and they said they couldn't transfer me to a level 2 tech because I wasn't listed on the account. This tech also told me that they allow anonymous emails on port 25, so I knew I was working with the wrong guy.

Yes, bottom line here is that Intermedia is incompetent. Which has been a question for a long time - why would anyone use Intermedia when Office 365 does the same stuff for lower cost but has Microsoft themselves backing it?