We’re running sbs2003 sp2 on a small single server network. Of the hundreds of clients we correspond with, there are just 3 that are unable to either reply to our emails or send us emails. This issue arose when we changed from receiving our emails by a pop3 account hosted by our ISP to having Exchange receive them directly by changing our mx records, etc. The incoming emails that are being rejected do not show in the syslog of our router, are not in our spam quarantine server, and are not in the SMTP log files. I disabled the Spamblocker in our router so all emails were being allowed to pass to the workstations, and the emails from these 3 clients still did not show either as junk mail or in the SMTP log files. In ESM I checked the Message Delivery Properties tabs and saw nothing that should reject any emails. On the Intelligent Message Filtering tab the SCL is set to 8. Any suggestions, I’m lost like the emails our server is rejecting?