"Works that cannot be recovered by readers (i.e., works without a source element) are cited as personal communications. Personal communications include emails, text messages, online chats or direct messages, personal interviews, telephone conversations, live speeches, unrecorded classroom lectures, memos, letters, messages from nonarchived discussion groups or online bulletin boards, and so on.
Use a personal communication citation only when a recoverable source is not available. For example, if you learned about a topic via a classroom lecture, it would be preferable to cite the research on which the instructor based the lecture. However, if the lecture contained original content not published elsewhere, cite the lecture as a personal communication."
"Citing Personal Communications in the Text. Because readers cannot retrieve the information in personal communications, personal communications are not included in the reference list; they are cited in the text only. Give the initial(s) and surname of the communicator, and provide as exact a date as possible."
(APA Publication Manual, 7th ed., p. 260)
(N. Smith, personal communication, April 8, 2020)
N. Smith said in her email ....(personal communication, April 8, 2020)