Where do I find out what my MX Record is?

Do you have a mail server (note: not a mail account, but a whole mail server which would host many mail accounts?) "MX" stands for "Mail Exchange" and it's purpose is to remove ambiguity in mail routing and/or ensure that mail destined for a mail server that isn't directly reachable on the public Internet will be directed to a gateway which can ultimately forward the mail to the right server.

The MX record is assigned to your domain name (e.g. "mydomain.com") but resolves to the specific host name either of your real mail server (provided it is publicly reachable on the Internet) or to a gateway mail-server (which resides on the public internet but knows how to forward email to your internal mail server(s)).

You can also define multiple MX records with priority numbers (e.g. one server is the preferred routing method but it will use another server is the first server is unreachable.)

None of this is stuff that would be on your own personal Mac.

The "Mail" application on your Mac is a mail client (not a mail server).

The address appears to be a Comcast IMAP & POP server (which means it'll hold mailboxes and/or mail for Comcast customers) but not an SMTP server (simple mail transfer protocol -- which it would need to run in order to exchange mail with other mail servers). In other words, it's not the right server that would be defined in an MX record.

If you had a mail server (something that speaks SMTP) it should get a defined host name. The MX record is defined at the domain level (e.g. mydomain.com), has a numeric priority (e.g. 10 is common), then the name of the server which handles mail (or mail forwarding) for the domain specified as a hostname (e.g. mail.mydomain.com or mx.mydomain.com).

You don't have to have a mail server for a domain. If you are operating a website for a small business where you just need to make sure you are able to get mail, you could set up an email account for the business and have mail forwarded there without the hassle of trying to create & manage a mail server.

There are services that will handle this for you. They'll either host your with your own mail domain, or they'll create a mail forwarder with your domain which forwards mail to some other address (which doesn't need to be in the same domain.) Both Google (www.google.com/a/) or DynDNS.org will do this and I'm sure there are lots of others. I thought MobileMe did it (they support personal domains) but that appears to be only for web (not mail.)

Are you running Mac OS X Server?

You've mentioned GoDaddy (hosting services), Comcast (home or business ISP), and you're mentioning Mac OS X Server (which isn't the same as Mac OS X -- it's a different version.)

Before we get too far, what is it that you have and are trying to do (e.g. why are you using GoDaddy, Comcast, and OS X Server and why do you want to find an MX record.)

Depending on what you have from Comcast, this can get tricky. Comcast normally blocks port 25 (both inbound and outbound) to stop people from setting up spam mail servers (or improperly secured servers that get exploited by spammers to do their dirty work) from within their network. They might not block it for business class service, but they do block it for home users (it's possible to set up, but only with the aid of an external service that handles mail forwarding. E.g. DynDNS.org can do it.)

Comcast's SMTP server is for mail running on the Comcast domain (e.g. email addresses that look like " username@comcast.net"). It doesn't handle email for non-Comcast email addresses.

To host your own mail in your own domain gets a bit tricky. You not only need a domain (which it sounds like you have), you'll also need at least 2 DNS servers hosting your domain (most pay an external service to host this). Also, Comcast blocks the old SMTP port 25 (at least they do for home ISP users - not sure if they block if you pay for a business class service.) so you'd need to setup mail on a port which requires SSL (587 is common) and have a mail forwarder service (yet another outside service you'd need to subscribe to.)

Lastly, but very important, you want to make sure your mail server isn't exploited by spammers who are always looking for a non-secure mail server from which to spam up the planet. Your mail server needs to be appropriately locked down. It should refuse to act as a mail "relay" for other mail servers. It should only accept messages for delivery from users who have accounts and should require those users to connect via SSL versions of SMTP (usually that runs port 587) and demand that they authenticate with a password or key.

If all of this sounds a bit overwhelming, it's because you've entered into a subject area beyond just normal "end user" computer knowledge. This is the sort of thing where most people either have in-house expertise that knows how to do this, or they outsource their mail hosting needs to a 3rd party (e.g. Google's business class services: www.google.com/a/ )

Google's your friend. Search for *MX Record*.