Our incoming SMTP traffic is restricted to mail "sanitized" by a mail hygiene service such as Postini. On our custom "INBOUND" receive connector, I have checked "Anonymous" under the Permissions tab. This works fine. No problem. Now when I initially configured this (and knowing even less about Exchange than I do now), I configured Authentication (under the Authentication tab) as follows: Checked Transport Layer Security (TLS) - I believe this was checked by default (not 100% sure) Checked Basic Authentication - I checked this because we did not coordinate TLS with our mail hygiene service. Nothing else (no sub-categories) are checked. QUESTION: If permissions are set to Anonmynous (or even if they were not?), does it matter what authentication modes are selected? I thought our mail hygiene service could not send to us without Basic authentication, but I'm wondering if that's correct. I prefer not to test by unchecking it either!

You dont need Basic Auth checkbox enabled unless they are actually authenticating to your server. By checking that Basic auth box, you are simply offering Basic authentication to the sending server via the ESMTP verbs, not enforcing it. Same with checking the TLS option ( but not the Domain Security checkbox). You are simply enabling that connector to offer Opportunistic TLS - not enforce it.