While Warren Buffett is very difficult to contact personally, it is possible to contact Berkshire Hathaway, the multinational conglomerate holding company with which he made his fortune.

Berkshire Hathaway has a public mailing address and email address that can be used to write to Buffett, although the communication will likely be read by one of his staffers and probably will not actually reach him. Buffett receives around 300 letters daily and does not personally read all of them. 

Berkshire Hathaway's public email address is berkshire@berkshirehathaway.com, and the mailing address is 3555 Farnam St., Omaha, NE 68131. Buffett occasionally responds to unsolicited investment proposals, as long as they meet the standards Berkshire Hathaway has provided for investment inquiries.

Warren Buffett has pledged a significant amount of his wealth to the Bill and Melinda Gates Foundation, and may also be reached by contacting that organization. The foundation provides grant funding for a variety of non-profit causes, primarily dedicated to improving health and education across the globe.

Buffett has considerable influence with this organization, and plans to donate to it from his estate upon his death. When contacting Warren Buffett through the foundation, address Buffett directly by name and send your correspondence to the organization.

Not every letter to the organization receives a response. Responses are more likely whenever the contact is relevant to the mission of the organization. The Bill and Melinda Gates Foundation is interested in providing grants, and any correspondence reflecting a non-profit need is more likely to receive attention from this organization.