A message box or e-mail that is filled with spam that is yet to be sent or submitted. Upon being sent or submitted, the spam is released into the chat box or message box for people to read.
In the martial arts tricking community, refers to when trickers who only do double twisting flips and twists, most of the time without any kicks at all.
Guy 1: "Look at that kid,all he does is spamdubs!"
Guy 2: "Yeah he never kicks at all, isn't that just bad gymnastics?"