See this example properly formatted in the QUT Cite tool.
Personal communications are cited in-text only, by providing the details below in the sentence, or in brackets.
A. A. Author, qualification/affiliation, form of communication, date
The manufacturer would not disclose the exact method used (S. Lorraine, Malva Global Foods, letter, February 7, 2019) …
…and D. Torres, MBBS, FRACP, stated that this is common practice in that clinic (email, August 1, 2020).
Personal communications are not included in the reference list, as they are unpublished and cannot be traced.
Provide the author's highest degree or their affiliation to establish the authority and relevance of the citation.