Shamelessly thieved from here.  Davak did a really good job in writing this up.  Carried this around in my wallet for the last couple of years.

People are often curious what the mail server is for a given domain. Here’s a quick way to find out…

    • 1. Click

Start

    • 2. Click

Run

    • 3. Type

cmd

    • in the textbox and hit enter

 

    • 4. In the command line type

nslookup

    • 5. Enter

set type = mx

    • 6. Enter the name of the domain you want to look up

 

    • 7. When you are done type

exit

Here’s an example looking up Microsoft’s mail server. You can see that microsoft’s mail servers are named maila, mailb, and mailc.*

C:\Documents and Settings\Tech-Recipes>nslookup
*** Can't find server name for address 192.168.0.1: Non-existent domain
*** Default servers are not available
Default Server: UnKnown
Address: 192.168.0.1

> set type=mx
> microsoft.com
Server: UnKnown
Address: 192.168.0.1

Non-authoritative answer:
microsoft.com MX preference = 10, mail exchanger = maila.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mailb.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mailc.microsoft.com
>

* – back in the day, circa 2004, Microsoft’s mail servers were called maila / mailb / mailc .  Not anymore.