Here are 3 examples that you can use for resignation letter as Assistant Professor -. Resignation letters should use the formal greeting: "Dear".The first sentence in the letter should state that you are resigning and when. We recommend sending emailed resignation letters in adobe (. Pdf) format, but a word (. Use singlespacing throughout your resignation letter. Align all paragraphs to the left. "Our country is facing a grave challenge," Freeland wrote in her resignation letter. Pope Benedict XVI was head of the Catholic Church and sovereign of the Vatican City State from 19 April 2005 until his resignation on 28 February 2013. Pope sends letter to prison inmates: Welcome Jesus into your hearts.