Try him on trainz.de. He's active there https://www.trainz.de/user/94-jagg/
Actually, I see him posting on many trainz forums, but trainz.de is the only one I remember for sure, LOL
You were most probably trying to send not visitor but private message. N3V made my PM messages box non functional by applying nonsense rule, that's why I suggested to use the visitor message instead, which works fine so far.