The official US Government website for overseas absentee voting assistance is the Federal Voting Assistance Program website at www.fvap.gov. It has a wealth of information about absentee voting, including the downloadable absentee ballot application (PDF 321 KB), state-specific instructions for completing the form, links to state and local officials, and a downloadable emergency ballot.
Please also see the State Department website on overseas voting here.
25 January 2016 Voting message (PDF 22 KB)
New Delhi: VoteNewDelhi@state.gov