I seem to be stuck between mail administrators pointing their fingers at each other for the issue of these probe failures. I just do not know how I can get to the bottom of this issue and get it resolved. I cannot determine if it is the mail server or the content filtering devices. The error is as follows: The reason for the problem: 5.1.0 - Unknown address error 550-'REJECTED - Invalid characters in sender = email address [@]' ############################ To unsubscribe from the LSTSRV-L list: write to: mailto:[log in to unmask] or click the following link: http://peach.ease.lsoft.com/scripts/wa-PEACH.exe?SUBED1=LSTSRV-L&A=1