I am looking for a word that is similar to the meaning of farewell or goodbye except that it has a negative connotation.
I find it hard to choose an appropriate word when I close communications with a person or organization that has affronted me when I really do not wish them to fare well.
Best Answer
Good riddance.
I'm done with you. (If you are. :-) )
For that matter, if this is in writing, "goodbye" may do what you want. It's pretty rare to close email or a letter that way, so this suggests closure. If you're speaking orally, then as drm65 says you can use tone of voice to convey your dissatisfaction.