import users gmail contacts to my website and send invitation to all their contacts

Hi i like to implement like tell a friend concept in my website.if user clicks the links it has to fetch their gmail contacts and has to send the mail to their gmail/yahoo contacts. how 开发者_Go百科can i do this? any sample site/link are welcome. Thanks in advance.

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For google contacts: Google Contacts Data API
For yahoo contacts: Yahoo! Contacts API

Also you can simply search for [Insert company here] contacts API on any search engine and I will bet you will find plenty of examples.