In my reading of the specification (RFC 5321, section 5.1), this isn't clear, and is therefore indeterminate and dependent upon implementation details.
My guess is that until the most preferred MX record is repaired (or the server is taken offline so that connection attempts fail), you are screwed. You can force this by some TCP hack-ish-ness. Create a manual route that points to nowhere. From: Kennedy, Jim [mailto:kennedy...@elyriaschools.org] Sent: Monday, July 02, 2012 10:00 AM To: MS-Exchange Admin Issues Subject: MX priority and failures/retries. I have my opinion on this but wanted some more. I have an outside domain that a user is trying to send to. They have 3 MX records with priorities. The lowest priority is messed up. The remote server answers on telnet but then hangs up a split second later with no error code sent. Should my exchange server then try the next priority listing in the MX record or should it continue to keep trying the bad record? --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com<mailto:listmana...@lyris.sunbeltsoftware.com> with the body: unsubscribe exchangelist --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to listmana...@lyris.sunbeltsoftware.com with the body: unsubscribe exchangelist
