Thanks, everyone. I was hoping for more war stories, or specific gotchas with more ornate configurations, so I'm suprised at the few responses. For example, I've noted that IMail has a queuing problem with HotMail advertising MX servers that don't actually accept mail, or that don't exist, which could come about with normal "downtime" on a mailhost that is still advertised in DNS.
Mark: As Bonno remarked, the MX records won't be served up round robin style, just the A records. So if you really wanted to spread the load evenly across your three big servers, you would instead: Have a single primary MX record, e.g. inbound.example.com Have 3 round robin A records pointing to the different IP addresses of your servers. The hostnames and HELO would no longer match, but I've never heard about the sender being picky about such things. You could of course reconfigure your servers to match the HELO to their new A record. You would leave the configuration of the 4th server as it has been already. Microsoft's DNS does round robin automatically; LH Soft's Simple DNS Plus will do it but the option has to be turned on. If some other DNS service like BIND or djbdns does round robin on other record types, that would be good to know... Pete: Thanks, "MX Classic" is probably what I'll do, depending on how the existing MTA continues to scale. I have the advantage of a private backbone and geographically separate locations and separate ISPs that I can take advantage of. I suspect that I'll find it's easier to keep the bulk of the traffic coming to my default location as an administrative convenience, even though if I used round robin to split the traffic between the two locations, I'd find some optimization on the private backbone, as 50% of the time, the stuff in one region would just stay in that region. Nick: Thanks, it's nice to know who's in the business. As it is, we're more of a DIY shop. Andrew 8) --- [This E-mail was scanned for viruses by Declude Virus (http://www.declude.com)] --- This E-mail came from the Declude.JunkMail mailing list. To unsubscribe, just send an E-mail to [EMAIL PROTECTED], and type "unsubscribe Declude.JunkMail". The archives can be found at http://www.mail-archive.com.