(From the Purdue Owl MLA Guide)
Interviews typically fall into two categories: print or broadcast published and unpublished (personal) interviews, although interviews may also appear in other, similar formats such as in e-mail format or as a Web document.
Personal Interviews:
Personal interviews refer to those interviews that you conduct yourself. List the interview by the name of the interviewee. Include the descriptor Personal interview and the date of the interview.
Smith, Jane. Personal interview. 19 May 2014.
Interview via email:
Give the author of the message, followed by the subject line in quotation marks. State to whom the message was sent with the phrase, “Received by” and the recipient’s name. Include the date the message was sent. Use standard capitalization.
Kunka, Andrew. “Re: Modernist Literature.” Received by John Watts, 15 Nov. 2000.