When ending a letter to a high gov't official with the phrase 'Respectfully Submitted', are both words capitalized, or just the first?

I would omit the word "submitted." One-word closings are fine.

Respectfully,

Sincerely,

Yours,

etc.

http://owl.english.purdue.edu/owl/resource/653/01/

When ending a letter to a high government official with the phrase "Respectfully submitted," it is customary to capitalize only the first word, "Respectfully."

To confirm this, you can refer to a reliable style guide or resource such as "The Chicago Manual of Style" or "The Associated Press Stylebook." These guides provide rules and conventions for capitalization in formal writing, including addressing government officials.

If you have access to an online database or subscription service like Grammarly or Merriam-Webster, you can search for the specific capitalization rules for ending a letter to a government official to get a more precise answer.