Andy Bakun in <1101549474(_dot_)31461(_dot_)37(_dot_)camel(_at_)alakazee>:
On Fri, 2004-11-26 at 22:13, Frank Ellermann wrote:
Andy Bakun wrote:
http://archives.listbox.com/spf-discuss(_at_)v2(_dot_)listbox(_dot_)com/200411/1186.html
What's that ETRN feature
ETRN and ATRN are, it seems, both essentially the same thing
They're very different, though both result in mail being
delivered via smtp from, typically, an isp's mail system.
With etrn, the user's client connects to the isp's server,
usually on port 25, and the server responds and closes that
connection. If mail is waiting for that node, the isp's server
then launches a separate smtp client session to effect delivery.
Thus, etrn requires the user to have a fixed ip address
assignment.
With odmr, the user's client connects to the isp's server,
usually on port 366, and authenticates securely (at least
cram-md5) before issuing the atrn [domains] command. If the
server has mail for 'domains' the direction of the existing
connection is reversed and mail flows from the isp's server to
the user's client. There's no risk of mail going astray with
odmr, even for clients with dynamic ip address assignments.
Afaiaa, mailkeep <http://www.mailkeep.com/> was the first
commercial odmr implementation.
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