Outbound Glossary
Blacklist
A public list of senders to refuse. Which list you land on decides whether it is a nuisance or a shutdown.
Blacklists, also called blocklists, are maintained by third parties and consulted by mail servers. Some are used by almost everyone and landing on one stops your mail reaching large parts of the internet. Others are used by nobody in particular and appearing on them changes very little.
So the first question after a listing is never how to get off, it is which list and who honours it. Delisting usually means fixing the cause and requesting review, and requesting review without fixing the cause gets you relisted within the week.