SAP CRM access using e-mail id - CRM7.0 EHP2

Hi ,

We are upgrading to CRM7.0 EHP2 (ABAP stack)  from CRM5.2..

Can anyone suggest is it possible to access SAP CRM system via e-mail id

(i;e external users ) authentication or alias name using only webui  ?

if possible , request to throw some light on the configuration and authentication.

Regards

Praveen