One can email Barack Obama through the White House's official website, WhiteHouse.gov. The online form enables visitors to send comments, questions, concerns or other messages to Barack Obama or his staff.
Barack Obama is, as of 2015, committed to making his the most accessible and open administration in American history. In addition to email, the White House accepts messages by phone or regular mail. The phone number to leave a comment is 1-202-456-1111.
For regular mail, the White House prefers letters that are neatly written by pen or typed on 8.5-by-11-inch sheets of paper in envelopes with a return address. The mailing address is The White House, 1600 Pennsylvania Avenue NW, Washington, DC, 20500.