Some of my clients are getting this error sporadically. Once they get it the first time they can resend and the message will go through. The following recipient(s) could not be reached: XXXXXXXXX on 12/2/2003 9:51 AM You do not have permission to send to this recipient. For assistance, contact your system administrator. <exchange1.mccormackbaron.local #5.7.1 smtp;550 5.7.1 Unable to relay for XXXXXXXXXXX> I have the box checked that says to allow all users who authenticate to relay regardless of the list above on my SMTP Virtual server. It seems to be happening with the same 5 clients but not all the time. I can't find anything helpful on the Knowledge Base. Can you offer any suggestions? Thanks.