I just started up with a linode account today, and am accessing it via IP address until the DNS changes have been made by the client.

The only things running on the old site are some static HTML pages, which have already been moved, and a mail server of some sort that does nothing except forward emails sent to that domain to exactly 2 email addresses.

So what would be the easiest way to 'prepare' my linode for a quick transition, given that all I want to do is run something that will accept email to 2 addresses at the domain, and forward them to 2 other addresses? What software would be best suited for this task?

Let's face it - email can be a real pain to deal with. I've worked with just about every MTA out there, and I don't think there's such a thing as a "simple" mailserver. Out of all of them, postfix seemed to be the most straightforward.

Anyway - if you really want to host this yourself, you could give postfix a try, though it seems like overkill if all you're doing is forwarding a few addresses. There may be a stripped-down MTA out there that is set up to just relay messages, but I've never heard of such a thing.

One thing to consider would be to, instead of hosting this yourself, to use Google Apps for your Domain. I've started using this for my personal domain as well as several domains for my clients, and I'm absolutely thrilled with it. The service is free, and you can easily set up the mail forwards you need.

...just my $0.02.

Where is the option to forward mail in the google apps control panel/dashboard?

To setup an email forward for one user:

User Accounts -> click user -> Add nickname

To setup an email list that forwards to multiple users:

User Accounts -> Create email list

This is actually incorrect. The nickname functionality just adds a user alias to the account. I'd use this, for instance, if you wanted to receive (in the same account) mail sent to joe@domain.com and jane@domain.com.

The best way to do this is just to create your desired user accounts, log into them and then in the user "settings" menu, you can set up forwarding.

Most MTAs will support a .forward file in a user's home directory. This file simply contains a destination email address where all of the emails are redelivered.