from
Jargon File (4.4.4, 14 Aug 2003)
bottom-post
v.
In a news or mail reply, to put the response to a news or email
message after the quoted content from the parent message. This is
correct form, and until around 2000 was so universal on the Internet
that neither the term `bottom-post' nor its antonym {top-post}
existed. Hackers consider that the best practice is actually to
excerpt only the relevent portions of the parent message, then
intersperse the poster's response in such a way that each section of
response appears directly after the excerpt it applies to. This
reduces message bulk, keeps thread content in a logical order, and
facilitates reading.