Whatever you do today definitely don’t fax a copy of Coretta Scott King’s letter to Mitch McConnell’s office at (202) 224-2499. It might jam the lines and that’d be a shame.
Don’t call his office at (202) 224-2541 and read the entire letter to whoever or whatever answers.
I’d also advise not mailing a TON of copies of the letter to his office until it looks like an assault from Hogwarts. The address you definitely wouldn’t send that to is:
Sen. Mitch McConnell
317 Russell Senate Office Building
Washington, DC 20510