We are running a SBS 2003 server with Exchange. Randomly throughout today, we would send an email and get the return message "550 Requested action not taken: No reason given". Got to love error messages with no explanation. I'm not finding anything on the internet about this. We didn't seen to have these problems last week. The difference is the server. I rebuilt the server and put the new one in this weekend. However, the router/firewall settings didn't change. Neither did, I believe the settings on the server. That is, I believe I replicated the old server pretty exactly, except the computer name. I would appreciate any thoughts any one has. Thanks, Stephanie

Run ExBPA Health Check on the Server to see if it finds any config issues. I would also suggest running SBS BPA. Sounds like you have configuration issue.MVP Exchange Server