We are using Exchange 2003 on our Small Business Server 2003. One of our users has complained that all emails from a particular email address have not been received. It is not a domain I am familiar with and is definately not on our blocked sender list/blacklist etc. I have checked the exchange server event log (I have enabled transport logs so can see when an attempt is made to deliver an email and if it succeeds), the anti-virus/anti-spam (Trend Micro Client/Server/Messaging Suite) engine running on the server and the Junk email folder on the users' PC - Cannot find anything! The other user does not receive a Non-Delivery-Report, so it seems as though the message is delivered, but I cant find any trace of it!
Some things worth mentioning:
- The sending/receiving message size limits are quite generous, about 20MB I believe
- We are using the blacklist from Spamhaus in Connection Filtering
- We are using Sender, Recipient, Sender ID and Intelligent Message Filtering, but none of them have any entries. Sender ID is set to accept messages and IMF is set to reject messages with an SCL of 8 or more.
- anonymous access is checked in SMTP Virtual Server properties, as well as Basic Authentication, Require TLS authentication and Integrated Windows Authentication. The FQDN checks out OK and the server is setup to perform reverse DNS queries. We are using our ISP's DNS servers for this lookup, as we do for all internet traffic.