Mozilla Thunderbird is an open source mail client and RSS reader made by the organization who produces the Mozilla Firefox web browser.
Setting up a new E-mail account in Thunderbird
NOTE: In all steps below, replace example.net with your domain name.
1. Open Thunderbird.
2. From the File menu, select New, then Account...:
3. In the New Account Setup screen, select Email account as the type of account, and click the Next button:
4. In the Identity screen, enter your Name and Email address in the spaces provided, and click the Next button:
5. In the Server Information screen, you can select from either a POP or an IMAP account. (see: IMAP or POP3? for help with this decision). Choose your account type, and then enter your Incoming Server and Outgoing Server (mail.<yourdomain>.xxx) in the areas provided, then click the Next button:
6. In the User Names screen, enter your full email address (e.g. you@<yourdomain>.xxx .. the whole thing!), and click the Next button:
7. In the Account Name screen, unless you want a fancier name, just click the Next button:
8. Finally, click Finish to exit the Account Wizard.
If everything is configured properly, and you still have problems sending then it's likely your ISP is blocking port 25. You will need to contact your ISP and ask them for help in setting up your E-mail for use with their outgoing E-Mail Relay.
Finish the setup and you're done!