Facebook, after unsuccessfully trying to get its users on its own email system, has thrown in the towel.
The social networking giant told AFP by email that it was giving up on email "because most people haven't been using their Facebook email address, and we can focus on improving our mobile messaging experience for everyone".
The company launched its email service in 2010, and in 2012 prompted an outcry by changing the default address for messages to users' Facebook addresses.
The project was seen as an attempt to be a "Gmail Killer," by getting members of the biggest social network to switch email accounts, but Facebook now admits it did not work.
"We're notifying people who use their @facebook.com email that the feature is changing," the company spokesman said.
"When someone sends you an email to your @facebook.com address, it will no longer go to your Messages on Facebook.
"Instead, the email will be forwarded to the primary email address on your account. (People have the option to turn forwarding off.)"
The news comes just days after Facebook announced a huge deal worth up to $US19 billion ($A21 billion) in cash and stock for mobile messaging service WhatsApp.
The deal bolsters the world's biggest social network - which has more than 1.2 billion members - with the 450-million-strong WhatsApp, which will be operated independently with its own board.
