It all depends on how you want to configure your relays. The default for sendmail implementations is that mail needs to be delivered to the lowest preference server. If a server with a higher preference accepts the mail, it will spool it and attempt delivery to that lowest preference mail server.
In the case of Exchange, you can easily have 2 IMS's with staggered MX preferences. In this case, either IMS will accept mail and route it internally (assuming full directory replication). If you look at the MX records for my company, you'll see that there are 4 MX's listed with increasing preferences. All 4 of those servers will accept mail and then forward it through our firewalls to internal relays which deliver the mail to Exchange. Roger -------------------------------------------------------------- Roger D. Seielstad - MTS MCSE MS-MVP Sr. Systems Administrator Inovis Inc. > -----Original Message----- > From: Mike Anderson [mailto:[EMAIL PROTECTED] > Sent: Thursday, May 29, 2003 10:22 AM > To: Exchange Discussions > Subject: The real story with Secondary MX > > > Hello, > > This is still a mystery to me. Could somebody explain, or > point me in the right direction, as to how this all REALLY > works? And also, to make sure things are configured > correctly (on the secondary server)? > > What is the overall process, on how mail gets routed - and > the criteria that has to be met, before a Primary mail server > is given up on, and then gets sent to the secondary server? > > Obviously, it all begins with DNS - you have preferences > using numbers. The lower the number, the higher the priority > the Mail Server is. So, the first MX gets a setting like > '10', and the secondary MX gets a setting like '20'. > > Once that is done - what really happens, if in fact, the > primary server is unreachable? Does the secondary Mail > Server actually need to have all the User Accounts and > Domains that the first server has in order to accept > messages? OR, does it accept literally everything, and then > spools the mail, once the Primary Mail Server is reachable > again. And that leads me to the next question - how does the > secondary Server know that it just accepted mails > (temporarily) for a primary server, and that it's supposed to > periodically contact the Primary - so it can offload all the > mail it's been accumulating this whole time? > > If somebody could explain the whole process, or refer me to > an article of some type, I would be very grateful. > > Thanks in advance, > > Mike > > _________________________________________________________________ > List posting FAQ: http://www.swinc.com/resource/exch_faq.htm > Web Interface: > http://intm-dl.sparklist.com/cgi-bin/lyris.pl?enter=exchange&t ext_mode=&lang=english To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Web Interface: http://intm-dl.sparklist.com/cgi-bin/lyris.pl?enter=exchange&text_mode=&lang=english To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED]
