abusive or insulting online is called
Early on in the age of the internet and chat rooms, the word flame began to be used to describe abusive messages.
Flames
abusive or insulting message
An invective is a highly insulting or abusive piece of language.
Using or containing insulting or coarse language
A player may be sent off for using offensive, insulting, or abusive language [toward anyone].
abusive
Draco called Hermione a mudblood - an insulting term for muggle-borns.
It might be called a rant.
It is usually referred to as cyberbullying.
a "hobo" because it rhymes and its insulting.
(abusive answer deleted)