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postfix is sending mail to the last preference mx record (ie:50 instead of 5)

Biggest problem is the domain its sending to, the last mx record is dead so the server doesn't respond.

I've tried to do a smtp test on the first few mx records and they accept connections.

How can I troubleshoot why its going to the last record, and how can i resolve (if its just skipping the rest and not because connections are refused)?

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Do you see any useful information in your postfix logs? – larsks Jan 20 '11 at 18:01

Postfix is RFC compliant and tries the MX with highest priority (lowest value) first. With one exception: caching. If Postfix encounters a problem (defer, reject) on the first MX it tries to deliver to the others. The first successful MX will be cached for a few hours (I think it was 24 hours), unless the cached MX will also fail.

So if postfix shows your symptoms it is mainly a DNS setup error or based on the caching "problem".

You can see the answer of the Postfix author to a similar question here.

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