009/6/10 Truth Seeker <truth_seeker_3...@yahoo.com>: > now to do flushing for a particular domain, i am trying to configure fast > flush service. in the documentation i found the following line, which i am > confused. > > could anyone explain this further > > As mentioned in the introduction, the mail is delivered by connecting to the > customer's SMTP server; it is not sent over the connection that was used to > send the ETRN command. > > i feel like they are mentioning about two connection? > i didnt understand which are these two connections? > then i feel like whenever we are sending a mail to a domain, its usual that > it will try to connect to that particular mail server to deliver it. in such > a case, why here they mentioned about 2 connections???
Disclaimer: I've never used fast flush before, I don't know much about it. Imagine a system, "X", that receives mail on behalf of a domain, it is not the final destination for that domain. The final destination, "Y", has an intermittent connection, like satellite or dialup. Rather than queueing mail for the domain and attempting to push it, it just holds it. When the final destination comes online, it can connect to "X" via SMTP and issue the ETRN command. That's it. "Y" may send mail via "X", or it may not. When "X" gets the ETRN command it attempts to deliver the queued up mail to "Y", because it must now be online. This effectively turns SMTP from a best-effort "push" protocol, to an on-demand "pull" protocol. It just happens to be convenient that the ETRN command can be issued via an SMTP channel. Someone please correct me if I've gotten any of this wrong.
