Huma Abedin told FBI the White House was informed when Clinton changed her primary email address
White House server could only receive emails from designated accounts
FBI showed Abedin an exchange between Clinton and an account she did not recognize, believed to belong to Obama
June 2012 email was titled 'Re: Congratulations' and took place on day Supreme Court upheld part of Obamacare
Abedin said she was shocked the email was not classified
Obama told CBS in March 2014 he learned about Clinton's private emails from 'news reports'