Enable SSL Encryption for Windows Live Mail (IMAP)
Activate SSL Encryption for Windows Live Mail using IMAP.
Open Windows Live Mail and select your 1&1 Mail Basic account that you have already created in Windows Live Mail.
From the Accounts tab, click on Properties.
Windows Live Mail start page
A new window will appear. Click on Advanced tab.
Account Properties overview
In the Outgoing mail (SMTP) field, enter 587 and check the box labelled This server requires a secure connection (SSL).
In the Incoming mail (IMAP) field, enter 993 and check the box labelled This server requires a secure connection (SSL).
When, finished, click OK.
For additional information, you may want to reference: