Customer Match will work this way – the system enables companies that users “already have a relationship with” to upload their email list to Google, where Google’s back end will do the hard work of matching those email addresses with Google Accounts in order to build your profile. This unique profile will then be the template for more specific and relevant ads to head in your direction.
This new initiative will enable various ad scenarios that opens the door for an advertiser to extend current customer relationships. In terms of your privacy, Google claims that the email addresses will be sufficiently hashed so that personally-identifiable information will be hidden. [Press Release]