Mail Delivery errors when posting here ???

For some reason I get the following e-mail every time I make a post here recently and not sure why: ------- This message was created automatically by mail delivery software (Exim). A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed:   lee@yun.yagibdah.de     SMTP error from remote mailer after MAIL FROM: <monty3@hotmail.com> SIZE=6478:     host yun.yagibdah.de [192.168.0.1]: 550 rejected:     administrative prohibition ------- This is followed by a copy of my posting to the newsgroup which does get posted. Not sure why it's being rejected and where this is coming from. Any clues?? Monty