1. Go to Mozilla Thunderbird, from the Tools menu select Account Settings.
2. Select Email account, and then click Next.
3. Enter your name and e-mail address.
4. Select POP or IMAP as the type of incoming server you are using. Your incoming server is mail.youdomain.com for POP, or for IMAP then Click Next.
5. Enter your e-mail address for the Incoming User Name, and Outgoing User Name then Click Next.
6. Enter a name for your email account and click next.
7. Verify your account information and click finish. In the Account Settings window, select Outgoing Server listed below your new account.
8. Type mail.yourdomain.com for the Server Name the default port remains the same (25).
9. Select Use name and password and enter your e-mail address. Thunderbird will ask you for your password the first time you try to send mail. Click OK.
That is it!

