Extended SMTP#ETRN

ETRN ( Abbreviation for Extended Turn ) is an extension of SMTP e- mail protocol for mail services from networks that are not always connected via a dedicated line to the Internet. It is defined in RFC 1985.

During a dial-up connection a ETRN -capable e- mail server to send and receive e -mail / s ( queues ) is contacted by a requesting e- mail server. ( Call flow between e -mail servers - not to be confused with the client-side connection setup as POP3. )

The ETRN command is an extension to the SMTP TURN command. The SMTP TURN command rotates about an SMTP connection so that the server delivers over an existing connection emails. Since the SMTP TURN command is a major security problem, instead of the ETRN command was introduced.

Syntax

ETRN [ character> ] The node name must be a full name of a domain, which is a CNAME resource record or an MX resource record corresponding to the DNS.

Possible responses from the server:

250 OK, queuing for node started 251 OK, no messages waiting for node 252 OK, pending messages for node started 253 OK, pending messages for node started 458 Unable to queue messages for node 459 Node not allowed: 500 Syntax Error 501 Syntax Error in parameter Examples

Server: 220 xyz.com ESMTP server Client: EHLO my.fqdn.com Server: 250 xyz.com Client: ETRN Server: 501 Command not accepted ... Client: ETRN myfqdn.com Server: 253 OK, pending messages for node 3 myfqdn.com started Web Links

• RFC 1985 - The definition of ETRN (English)

• Internet e -mail protocol
• Abbreviation