Short for On-Demand Mail Relay, an e-mail service that allows a user to request e-mail from any internet connection by using a dynamicIP address as opposed to a static IP address. With OMDR, the user connects to an ISP that supports OMDR, authenticates and then requests e-mail. When the user requests e-mail, the roles of client and server reverse and normal SMTP operations proceed.
ODMR also is called ATRN, short for Authenticated Turn.
