Do SharePoint™ users have a mailbox

From mail2web.com Wiki

When adding users to your SharePoint site, the username will appear in the format of name@domain.com.  However, this does not mean that it is also an email address.  This is simply a identification method for SharePoint users on your domain.  In this example, name belongs to the organization called domain.com.  By default this user does not have any mailbox associated with it.

However, it is possible to add email service for this user if you wish.  Please refer to the article entitled "How can I add an Exchange to my existing SharePoint™ Services account?"