Personal communications should be included in the text of your document, but they should not be included in your reference list. It is recommended that permission is sought from the source/author of a personal communication if you wish to include quotes in your text. The details you need to include when referencing in text are:
Conversation
In a conversation with a colleague from the School of Population Health (Jameson LI 2002, oral communication, 7th August)...
Letter
As stated in a letter from B.J. Samuels, MD, in July 2002...
Smith P. New research projects in gastroenterology [online]. E-mail to Matthew Hart (mh@hospital.wa.gov.au) 2000 Feb 5 [cited 2000 Mar 17].