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I have a server and sometimes it rejects mails (Relay access denied)

I added a second MX entry (MX 20). Now the question:

If the outgoing server gets a Relay access denied from MX 10 does it try to send to MX 20?


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The MX records have nothing to do with your servers rejecting relay attempts. Furthermore, if the servers are rejecting the email that should be telling you that the email is getting to the servers which is another indication that there's nothing wrong with the MX records. MX records tell a sending server where to send email, they have nothing to do with how the receiving servers handle that email. If your servers are rejecting attempts to relay through them from external sources, then that's what you want it to do. You don't want your servers acting as open relays.

Perhaps you can give us more details on these rejections that you're seeing.

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So I have 2 smtp-relays which send mails to a internal server. the first server is sending Relay Access Denied State 14 to others, because of updates and curious backup options (while backup the smtp server cant read the config file for 3-4 minutes). If this happens I want the second smtp server to receive mail (its not a backup server for this purpose only). They both have MX 10 as record. And my question is if other SMTP servers will try the other SMTP-Server if the first one does say "Relay access denied" – Phoibe Mar 27 '11 at 19:28

I'm not 100% sure about this, but I believe that the secondary MX will only be used if there's a network connection issue with the primary. SMTP errors don't cause it to fail over in this case, and when the sending mailserver attempts to deliver the mail again (if it does) it will do another MX lookup at that time, likely reconnecting to the same server as the first time around.

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Some (more permanent) SMTP errors also cause the primary MX to fail and the secondary to be tried AFAIK.

SMTP errors are comprehensive and can even include reports of no disc space.

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