Learn how to enable SPAM filtering in your 1&1 WebMail account to prevent unwanted e-mails from crowding your inbox.
First, log into the 1&1 WebMail interface at http://email.1and1.com/ using your full 1&1 e-mail address as the username and the account's password.
Click the Configuration gear icon toward the top-right of the page and select Edit Settings.
Webmail configuration menu
Select Anti-SPAM from the settings page.
Webmail settings page
Select a Spam Protection level from Low to High, or custom for advanced users. A description is provided for each setting level after it is selected, to help you understand how your mail will be filtered.
Anti-SPAM settings page
For additional information, you may want to reference: