What is Open Relay Blocking?
In an attempt to reduce or eliminate spam received by their users e-mail system administrators are increasingly using Open Relay Blocking to filter e-mail arriving at their site. Several scanning or filtering approches can be taken; an increasingly common approach relies on outside organizations to detect open relay sites. There are several groups that actively scan the Internet for open mail relays. When an open relay is detected, it is added to a list of known open relays, and the open relay blocking organizations provide a simple interface that allows an SMTP server to determine whether incoming email is coming from a host on their list of open relays – if so, the email is dropped, usually with some sort of bounce message that describes why the mail was dropped. In a classic case of throwing the baby out with the bathwater, ALL e-mail from the”blacklisted” host is discarded, without regard to the content of the e-mail message. Currently, for example, the Xerox Corp. is discarding al
