On Fri, Apr 04, 2008 at 11:21:46AM -0700, Paul Hoffman wrote: > Or, you can be more specific. What is the problem of a host that is > never expected to be on the RHS of an email address expected to have > an MX record? That's an honest question, given that it has been over > 12 years with the current setup.
This message came from [EMAIL PROTECTED], which is such an address. We need to find the place to drop a return-to-sender: Before 2821: lookup an MX record for $RHS If not found: lookup the address of $RHS and pretend it was an MX. During 2821: lookup an MX record for $RHS If not found: lookup the A-record(s) for $RHS and pretend it was an MX. After 2821: lookup an MX record for $RHS If not found: currently under debate. a) stay with looking up A-records (i.e. no AAAA fall back, only A) b) change back to looking up addresses (i.e. A and AAAA fall back)
