In-text: Mr. L. Bekker confirmed this by email on 30 May 2014 or Bekker (2014) confirmed this… or It was confirmed that … (Bekker, 2014).
Reference list: Author, A. (date of message). “Subject of message”, email to recipient’s name, for example:
Bekker, L. (30 May 2014). email to Rehana Prinsloo.