The ETRN command stands for Extended Turn and is an SMTP Service Extension specified by RFC 1985.
What it really does is: You have 2 MX record in the DNS server, one with a higher degree than other, so when a mail is sended through any SMTP server, it asks the MX records for the specified domain, and it receives 2 records, so it tries to send the mail to the first one (in this case your own server), so if it doesnt reach its destination, it alternates the email to the second MX record, (Your backup mail server). So the backup mail server only receives the mail, and stores it for a queuing time period preestablished by the system administrator, so in that time period, it tries to send the email to the primary MX record. In between that times, you can call the ETRN command, just telneting the IMAIL server like "telnet imailserver 25" after that "etrn domain.com" and then the server starts the transfer of all queued messages. So if your server goes down, the backup server automatically receives all of the email, but before that you have to obviously preconfigure the backup server. ----- Original Message ----- From: "Matthew Lohr" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, December 04, 2001 11:26 AM Subject: Re: [IMail Forum] ETRN (backup server) for mailservers > Ok is this to say that the MS Smtp service will do ETRN. I am not sure I understand. I thought I understood but now I am lost. And one more question to make this more confusing the downed vs not always online server. If my server goes down due to a network outage or say crash or my isp is down does that qualify for not always online? I am trying to make my service more redundant but have so many other things to dedicate my time to so can I get some clarification here > > > ---------- Original Message ---------------------------------- > From: Len Conrad <[EMAIL PROTECTED]> > Reply-To: [EMAIL PROTECTED] > Date: Tue, 04 Dec 2001 06:07:17 -0600 > > > > >>I've read Len's website on setting up a > >>FreeBSD-based ETRN servers when the current > >>mail server is down. > > > >hmm, ETRN is not for "down" servers, but for servers that are not always > >on-line, say on dial-up lines. > > > >>However, I'd like to build a backup MX server > >>but running on Windows 2000. > > > > > > > > > ________________________________________________________________ > Sent via the WebMail system at lohrtech.com > > > > > > Please visit http://www.ipswitch.com/support/mailing-lists.html > to be removed from this list. > > An Archive of this list is available at: > http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ > > Please visit http://www.ipswitch.com/support/mailing-lists.html to be removed from this list. An Archive of this list is available at: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/
