To set up Mozilla Thunderbird you will first have to acquire the necessary
information by following the FAQ:
What information is required to set up e-mail clients for POP3?
1. Open Mozilla Thunderbird. Click Tools -> Account Settings.
2. Click Add Account.
3. Choose Email account and click Next.
4. Enter your name and e-mail address. Click Next.
5. Choose POP and enter pop.1and1.com as the incoming server. Click Next.
6. Enter your e-mail address and click Next.
7. Enter a name for the account and click Next.
8. Click Finish.
9. Click Outgoing Server (SMTP) and change the User Name to your e-mail address.
(Note: Username and password box has to be checked.) Click OK.
10. Now when you click Get Mail you will be prompted for the password.