Prepared by Elisabeth Lindsay.
LSASE is an acronym referring to "long, self-addressed, stamped envelope." The acronym SASE is also used, "stamped, self-addressed envelope," indicating no size requirement. The abbreviation is often used relative to correspondence and the request for information, placing the burden of postage on the person making the request.
Genealogists requesting information are often instructed to submit an SASE or LSASE, along with any applicable fees. The LSASE requirement has become common to facilitate the return of documents that may not fit in smaller-sized envelopes.