Messaging someone during a bidwar is not against the rules per se, but if someone were to do it often and is being reported for it, he would be warned and eventually sanctioned. The content of the messages is as important as the intent.
I had this pretty often before and I personnaly would not allow such a behaviour. Sometimes you get messaged pretty short "threats" like "player xy 1.2 mil" - I am pretty sure you would not sanction those GMs even if they did it every time and were reported more often than not.
So if you ban/fine those angleshooters I would very much appreciate it.
Größter Knecht aller Zeiten aka His Excellency aka President for Life aka Field Marshal Al Hadji aka Lord of All the Beasts of the Earth and Fishes of the Seas aka aka Conqueror of the Buzzerbeater Empire in Europe in General and Austria in Particular