Unix Tip: Mail loops back to me

By Sandra Henry-Stocker, ITworld.com

Many systems administrators have run into errors in their syslog files that complain that mail is looping back, suggesting a possible MX problem. The common cause of this problem is that a server is receiving email for a domain that it doesn't recognize as its own. Then, when the server looks up the MX address for the intended target (in order to send the mail on its way), it notices that the MX record is one that identifies the mail exchanger as the system itself.

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