How do I delete an email that has failed Reverse DNS Lookup?
Some messaging systems verify the existence of the e-mail domain of the sender before they accept a “Mail from: user@domain.com” Simple Mail Transfer Protocol (SMTP) entry at the beginning of a new message delivery session. If the domain name cannot be resolved by means of Domain Name System (DNS), the session is disconnected and an error 501 is generated. This behavior is mainly used to prevent you from receiving spam (unsolicited e-mail messages). Microsoft Exchange Server 2003, 200, and 5.5 do not use this feature. For Exchange Server, the Perform Reverse DNS Lookup for Incoming Messages option does not have the same function of the feature that had been previously described (the function to prevent the receipt of spam e-mail messages). When the preceding option is used, Exchange Server performs a DNS query to resolve the originating Internet Protocol (IP) address of the incoming messages to a host name. Then, the host name is attached to the headers of e-mail messages.
