Launch Mozilla Thunderbird. If it is your first time launching Mozilla Thunderbird, the Mail Account Setup Wizard should appear and you may skip to step 4. Otherwise continue with the next step.
From the Mozilla Thunderbird window, select ToolsAccount Settings.
Mozilla Thunderbird Tools options
At the bottom-left, select Account Actions and then Add Mail Account.
Enter Your name, your full Email address and your 1&1 Mail Basic address Password. Check the box for Remember password if you do not wish to enter your password every time when checking or sending E-mail. Then, click the Continue.
Mail Account Setup
Suggested settings may be provided for you. Be sure to select POP3 to view the suggested POP settings. In this example, the suggested settings are incorrect so we will click the Manual Setup button to enter the correct information.
Mail Account further details
Enter pop.1and1.co.uk as the Incoming Server hostname and select 995 as the Incoming Port Number. Select SSL/TLS from the SSL drop-down menu and select Normal password from the Authentication drop-down menu. (A)
Enter auth.smtp.1and1.co.uk as the Outgoing Server hostname and choose 587 as the Outgoing Port Number. Select STARTTLS from the SSL drop-down menu and select Normal password from the Authentication drop-down menu. (B)
Enter your full 1&1 E-mail address as the User Name. (C)
When you are finished, click Done.
Click OK to save your settings.
Account Settings overview
You will see your newly-added account under Local Folders.