Is possible by default in Drupal 7 to have more than one email associate for a user ?
In the Users table, 'mail' - the field for email addresses, is unique, as it's tied to other criteria to control account management, login, logout, etc.
So depending on what you are trying to accomplish, I dont think you could have more than one email control one account without some custom database changes.
However if you simply want to link an account to multiple email addresses, perhaps this is as simple as an 'email address' field for the profile. Adding unlimited to that field for the form would invoke the 'add another' and the user could simply have as many as they needed.
If you wanted that person to be able to login with any of those email addresses, then a quick module could link the fields together so that the email addressed used had a primary account referenced by it, and, then would proceed with login.
Or, I could be way off - what are you ultimately trying to accomplish?