Like you, I have also been running Microsoft Entourage - a part of the Microsoft Office for Mac suite - for quite a while. I've tried switching to other apps a few times, including spending about four hours trying to migrate to Apple Mail a while back, but have not yet found an application that has the power and flexibility of Entourage, especially with mail filtering, multiple accounts, multiple signatures, and so on.

It definitely has its bugs (I'm amazed that it still picks the wrong spot in the message to insert a signature, even after years of updates!) and the central unified database of messages is a definite problem and most of my tech savvy friends are amazed that I've never had a database problem or lost hundreds - or thousands - of messages from an archive because of a corrupted database problem.

I've also written various tutorials on how to work with Entourage too, which you can find here: Entourage help.

Now, on to your question! Here's how I recently added a new account to my own Entourage setup.

The first stop is to choose "Accounts" from the "Tools" menu:

Now you can see the accounts I already have set up:

Click on "New" on the top left and you'll find that there is a wizard that'll help you add a new account, actually:

Unless you know otherwise, don't check "My account is on an Exchange server", but do fill in the name & email address, as I have done above.

Then click on the small right arrow on the lower right corner and see if you get lucky:

As you can see, I didn't. The program informs me that it couldn't determine the necessary account information from the email addr I entered. Weird, but okay.

Keep clicking the right arrow...

Your ISP or IT person should have given you all this information. Fill in the form, click the right arrow again.

Cool! That's what we want, to verify the settings entered. Click on "Verify My Settings" and after a few seconds you should have a green light.

Darn! As you can see, the incoming mailbox configuration is fine, but the outbound mail isn't set up properly. Not good!

Fortunately, however, I only needed this account to check a mailbox on an older server so I don't need the outbound capability. Instead, I just click on the right arrow again.

To my surprise, I get this:

I click on "Skip" and it's set up, all but me specifying a name for it and specifying whether it should automatically be polled or not:

Finally, done. Click "Finish" and you should have a new account setup within Microsoft Entourage, as you see I have done here.