Round-Robin for mail/smtp hosts

[Kevin Darcy]

For *sending* mail, this isn't a problem at all. In fact, we use a
multiple-A-record name internally for all outbound SMTP connections from
browsers, Unix servers, mainframes and the like (our primary internal mail
system is *not* SMTP-based, so the traffic on this SMTP "side-channel" is low
enough that we don't require a more sophisticated load-balancing solution).

When you say "checking" mail, though, this implies remote access to a mailbox,
via POP or IMAP or whatever. In DNS terms, this doesn't matter, but in mail
terms you of course need to make sure that those mailboxes are shared properly
on the various server(s) included in that round-robin name, and can handle
potential conflicts, e.g. being updated in incompatible ways on two different
nodes simultaneously.


- Kevin

Matt Prigge wrote:

> Hi All,
>     I have seen many discussions on this list about using multiple A records
> for load balancing and redundancy in HTTP/WWW applications. However, I
> wanted to know if there are any problems with using them for other
> applications such as balancing between two outgoing mail servers or between
> two pop/imap servers. I personally cant think of any (which is why Im
> asking). Please note that I am not talking about using multiple A records
> for MX hosts, just about the address that a client might punch into Outlook
> Express or Netscape to check and send their mail.
>
> Thanks!
>     - Matt Prigge