This is usually what happens when people see you spam. The intention is to have eg. ALL your I.S.P.s members could be denied their email, and possibly other, services. In an extreme case your I.S.P. could go out of business. Your I.S.P. would probably cancel your account.
Spam tends to annoy a number of people on the internet.
The intention is to overload an I.S.P.s email facilities. Most people who do this aren't too bothered whether one, or both happen. As long as the spammer is put out of business, even if only for a temporary period. Usenet Death Penalty. There are people who trace where just about every spam, email and usenet, originates from.