SMTP Service Extension for Remote Message Queue Starting

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." To learn the current status of any Internet-Draft, please check the "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). 2. Abstract This memo defines an extension to the SMTP service whereby an SMTP client and server may interact to give the server an opportunity to start the processing of its queues for messages to go to a given host. This is an attempt to fix the security problems with the TURN by creating a new command ETRN that places the emphasis on the server instead of the connection. This extension is meant to be used in startup conditions as well as for mail nodes that have transient connections to their service providers. 3. Introduction The TURN command was a valid attempt to address the problem of having to start the processing for the mail queue on a remote machine. However, the TURN command presents a large security loophole. As there is no verification of the remote host name, the TURN command could be used by a rogue system to download the mail for a site other than itself. Therefore, this memo introduces the ETRN command. This command uses the mechanism defined in [4] to define extensions to the SMTP service whereby a client ("sender-SMTP") may request that the server ("receiver-SMTP") start the processing of its mail queues for messages that are waiting at the server for the client machine. If any messages are at the server for the client, then the server should create a new SMTP session and send the messages at that time.