From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <81c03baf080b2b71267e6095a9927d2c@coraid.com> From: erik quanstrom Date: Tue, 16 Jan 2007 15:31:31 -0500 To: rsc@swtch.com, 9fans@cse.psu.edu Subject: Re: [9fans] $smtp dns failure MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Cc: Topicbox-Message-UUID: 04d5556e-ead2-11e9-9d60-3106f5b1d025 i'm not sure why you're taking offence. to me it seemed clear that mxlookup differs from the algorithm in section 5 of 2821 and what other mailers do. the rfc doesn't say that we need to abort of the mx lookup fails. i think this is important because it's possible for an mx lookup to fail and an a/a6 lookup on the same name return results. i had quite a bit of trouble with this when using level-5's dns last year. in addition, a quick inspection of postfix' src/smtp/smtp_addr.c seems to confirm that they perform a/a6 lookup on mx lookup failure. since other smtp agents don't notice the misconfiguration, we are left to find it. anyway, i put the effort into pulling together my notes from last year on this to help, not to annoy. hopefull this information is not a further annoyance. - erik