MX records and multiple IP addresses

[Keller, Richard (CIT)]

We have a client who is requesting the following:

They currently have an email server with an MX record pointing back to it.  So
let's say the record is mailserver.nih.gov. IN MX 10 mailserver.nih.gov.  They
wish to have another email server, mailserver2.nih.gov, that will be on the same
IP address, but will be used for IIS web access to exchange.

If they are registering mailserver2.nih.gov to the same IP address as
mailserver.nih.gov will it need another MX record that points to mailserver2?
In other words, mailserver2.nih.gov. IN MX 10 mailserver2.nih.gov.  Or, should
the MX record point back to mailserver.nih.gov.

In addition, will multiple MX records on the same IP address cause any kind of
problems routing e-mail or with name resolution?

Help on this will be most appreciated.

Richard Keller
National Institutes of Health