Outlook Syncs Contacts to CRM ignoring Required Field rules

Currently if I created a contact with only a first name in Outlook, I can sync that contact to CRM. This poses a problem when I go to CRM because I have a contact missing required fields (last name, email..etc.). 

Looking at the bigger picture, this allows duplication if same contacts are not fully detailed in Outlook and sent to CRM by multiple users. 

Any ideas on this? Suggestions would be greatly appreciated. Thanks.