The Bluebook provides table of examples of citations for unpublished and forthcoming sources, including such materials as unpublished manuscripts; dissertations and theses; letters, memoranda, or press releases; e-mail correspondence; forthcoming publications; and working papers. See R17.1, p. 169. Additionally, there are some examples on The Bluebook's Quick Style Guide.
When referencing this type of material, it is important to specify the document type and include the full names, titles, and institutional affiliations of the author and recipient. Additionally, abbreviate the title and institutional affiliation based on the guidelines provided in tables T6 and T11, and elsewhere in The Bluebook. Also, note using the Internet archival method per R18.2.1(d).
See Press Release, U.S. Dep’t of Just., Federal Officials Decline Prosecution in the Death of Freddie Gray (Sept. 12, 2017), www.justice.gov/opa/pr/federal-officials-decline-prosecution-death-freddie-gray (describing the events leading to Freddie Gray’s death).
When referencing personal email messages, treat them similarly to unpublished letters (according to R17.2.3). It may be necessary to include the date of the message and the timestamp for precise identification. It would be advisable to include archival information in parentheses. While not mandatory, you can include the email addresses of the sender and recipient if there's a specific reason to do so.
E-mail from William Henry Harrison for President 1840, to Potential Donors (July 4, 1840), (on file with the author).
When referencing speeches, make sure to include the speaker's full name, job title, and organization if available or relevant. Also, include the title of the speech, specific reference (if applicable), and the date. Use abbreviations for the speaker’s title and institutional affiliation as per the guidelines in T6 and T10.
Senator Robert F. Kennedy, Day of Affirmation Address at the University of Capetown (Jun. 6, 1966).