Click here for a guide on checking your email settings
Click here for a guide on changing your email password

Step 1 - Click on Tools > Accounts

Step 2 - Click on + > E-mail

Step 3 - Add your domain settings

Step 4 - Set outgoing server Authentication to Use Incoming Server Info

That's it! To test your email is working, simply send an email to that account from another and vice versa. Easiest thing to do is send yourself an email, for example to [email protected] from [email protected]