Where / How to store email address in SharePoint 2010 when using Claims

When you are using Claims based authentication method, the user is never added SharePoint SiteCollection unless the user has logged to the site for the 1st time. However, when a user logs into the site for the first time, its identifier is only stored in a UserList List.

If you have a need to send emails to user as per of workflow or alert or anything, you need to find a place to store them. You could easily use the UserList to store this information. As a user is entering your site, you could write code to query the claims to extract email address the user primarily has and then extract that value and store it to the User List.

The location of this list http://myserver/_catalogs/user/Simple.aspx

Specail Consideration with this list:
- User List is very notorious as to when it updates the data.
- Initially when you create a new Site Collection, this list shows less than 15 columns and then a timer job runs and it adds around 40 more columns to the list.
- This list can only be seen by Site Collection Admin and above.
- In order to update to this list, you should ue run with elevated privs.

I will post some sample code soon.