Synonyms for Newsletter:

n.

chain letter, enclosure, cover letter, billet doux, acknowledgment, air letter, Dear John letter, dead letter, answer. •chronicle (noun)
description, catalog, archive, epic, newspaper, journal, recital, memo, Bank book, ledger, index, scrapbook, biography, album, yearbook, enumeration, log, docket, account, diary, inventory, book, anecdote, notebook, autobiography, statement, chronology, register, daybook, record, narrative, history, calendar, chronicle, Cashbook, memorandum.
•communication (noun)
newssheet.
•magazine (noun)
gazette, review, organ, periodical, newspaper, circular.
•newsletter (noun)
journal, bulletin, report, newssheet.
•publication (noun)
dissemination, propaganda, bulletin, periodical, advertisement, broadcast, gazette, notice, post, report, publication, review, commercial, promulgation, newsmagazine, book, journalism, herald, handbill, announcement, organ, circular, promotion, brief.

Other synonyms:

•Other relevant words:
chain letter, air letter, newssheet, dead letter.