While sending mail to a domain, if we get the error below, the issue is with the domains that wont be listed in /etc/localdomains

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2010-07-10 00:14:39 [26363] lowest numbered MX record points to local host: (while verifying <test@\ from ]:50329)
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Fix--> Add the domain in /etc/localdomains.

/etc/init.d/exim restart

and try sending mail.