Request permission to quote the material. Usually this will be granted, but sometimes correspondents send email under the assumption that they are conducting a conversation that will be shared only between the two of you.
Type the quoted material into your manuscript, placing quotations around it to indicate that someone else wrote it. Place a superscript numeral or symbol at the end of the quotation.
Place a corresponding numeral or symbol at the bottom of the page above the footer space. Use the following format, found in the Purdue OWL (see references): Kunka, Andrew. "Re: Modernist Literature." Message to the author. 15 Nov. 2000. E-mail.