Answered by John, Hiring Expert at DuPont, on Tuesday, May 14, 2013
Thanks for the question. Yes, you should include your address and the company address on an e-mail cover letter. Even though it is an e-mail, it is still considered official correspondence.
I would make sure that you understand the preference of the company when submitting cover letters. Some larger companies require applicants to submit a resume and cover letter in preferred formats, as they are uploaded into an applicant database. Smaller companies may prefer alternate application formats.
Regardless of the preferred method, the application may be your first interaction with a company. Be as professional as you can to make the best first impression.