Personal communications, including email and text messages and direct messages sent through social media, are usually cited in the text only; they are rarely included in a reference list.
In a parenthetical citation, the terms personal communication (or pers. comm.), unpublished data, and the like may be used after the name(s) of the person(s) concerned, following a comma. If the medium is important and not mentioned in the text, it may be incorporated into the parenthetical reference.