Click the Manage E-mail Addresses link from the Mail panel.
Manage E-mail Addresses
Click the Create button next to 1&1 Mail Business accounts located at the bottom of the page.
E-mail overview page
Enter the e-mail address name you wish to use and select a domain for the e-mail address. Fill out all of the required fields. If wanted, check the boxes to activate Virus Protection and 1&1 Anti-SPAM. When complete, click OK.
E-mail address details
If successful, you will be presented an overview of the account settings. Click Go To E-Mail Overview to navigate to the E-mail overview page.
For additional information, you may want to reference: