outbound mail being tagged as spam

Mostly inbound spam is identified by checking if the server sending the email is properly configured in DNS. This means that if you do not have this configured properly you might have problems when sending outbound email.

Configuring a single exchange server

The Exchange server should have its own SNAT setup. If are using a lower end firewall you may have to use the default external NAT address of your firewall. This is not ideal but it will work. Make sure that TCP port 25 is open and outbound for this address.

Determine a non conflicting and valid name the server will have.

Modify the server to report that name.

• Open Exchange System Manager
• Navigate to the SMTP Virtual Server
• Choose "Properties" on the SMTP Virtual Server
• Click on the "Delivery" tab
• Click on the "Advanced" button
• In the fully qualified domain name box type the hostname that you chose.
• Click OK
• Click OK
• Restart the SMTP Service

Configure DNS

• Add a PTR (reverse) record for the server hostname for the SNAT address.
• Add a record for the server hostname for the SNAT address