Brian Cryer's Web Resources

Open Relay

Open Relay
A mail server that will route e-mail from any originator without the need for authentication. Spammers will often search for open relays as a means to send e-mail because it makes them harder to track down. Most (if not all) mail servers can be configured to prevent them from being used as open relays.

cf RNDR.

For more information see:

  • www.ORDB.org - Open relay database. Allows servers to be tested (to see if they are open relays) and individual servers to be looked up to see if they are known open relays.
  • http://support.microsoft.com:80/kb/324958 - How to block open SMTP relaying and clean up Exchange Server SMTP queues in Windows Small Business Server.