CiviCRM Community Forums (archive)

Hello folks,
We currently have Civi set up with First, Last, and Email as the Strict Dedupe rule, making those three fields the unique key for contacts.  We have a desire to change this so that Email alone is unique - no two contacts can have the same email address.  We want to use email as their login to our extranet, which links to their Civi contact record.

I'm having issues figuring out how this will work with Event Registrations and areas we use the API with (importing donations/contributions, etc).  I would like to get some strategies of folks who are going the same route (maybe due to Drupal accounts or otherwise).

If we have just Email be the unique identifier (making it the only field in the default strict rule), if a person registers using an existing Contact's email (because they share an email address or just maliciously) during Event Registration, it seems Civi will go ahead and overwrite the existing Contact's information - so the name and history of events/donations will belong to this new person.  Here is the scenario I'm thinking of:
1. Papa Smith sponsors a child monthly and donates to us with email = smithfamily@none.com.  He gets into Civi, no problem, gets ID = 10.
2. Mama Smith then donates to us with email = smithfamily@none.com.  Civi sees the email matches ID = 10, so it updates the Contact's information, including the names.
3. Kiddo Smith then registers for an Event with email = smithfamily@none.com.  Civi sees the email matches ID = 10, so it updates the Contact's information again, including the names, passport, everything.

Am I thinking about this the right way?  How are people handling this situation if they want to make Email unique in Civi?  I'm trying hard to avoid having Civi simply create duplicates and forcing an admin to dedupe all the time (that uses up a lot of our time nowadays).  I would appreciate some help in thinking this through ... thanks!

Well, our goal is to stop that behavior and have people use unique email addresses.  So we want to force that change (no gobbling up my cake ).  That's why I'm wondering how we can make this happen the right way.  We're convinced we should do it, just need to know how to implement it. 

How do others who have this uniqueness set things up in Civi so it checks appropriately without messing up a contact's information?