The purpose of farewell threads are to tell your friends in the community that you will not be able to continue actively using the forum for a period of time.
HOWEVER, a farewell thread is not:
-A "screw you" to the community, the staff, and/or specific members or voicing ill will
-An incredibly vague and/or short bye
-An advertisement for another forum
All of these threads will be closed (and possibly deleted depending on severity). Additionally, a farewell implies leaving. If you are implying that you are gone for good and yet are replying to your own thread for days on end, then there clearly is some sort of problem.
It is always a sad time when a member of the community has to leave, so please don't corrupt what should be a thoughtful farewell into spamming and flaming. If you can not make a farewell thread without spamming and flaming, just leave quietly.