I've run in to this issue where we now have two ISPs each with their own router on our network. we have multiple exchange servers and DNS servers on our internal network as well (one DNS server for each domain). Prior to the addition of the second ISP our exchange servers and DNS server routed mail and DNS requestsout one router and all was good. We now have one of the exhcange servers (also a DNS server for that domain) and a new exchange server pointing to the new ISP & Router.I can browsethe internet from the servers when the gateway is pointed to the new router,howerverI can not recieve incoming mail when the exchange servers DNS setting is pointed toits self. IfI point it to a second DNS sever that resolves DNS with our older ISP it works fine.I can telnet on port 25 to the exchange server via domain name and ip adderss (from a completely seperate ISP and network)DNSserver's fowarders IPs are set to the address the ISPs gave us.MX records at new ISP look correct (comparable to how our older mail server is set up to with our working setup)ISP created ptr records?Any idea on what to try next ????ThanksBen Leslie

Hi Ben, Please make sure you have registered your DNS record properly on public network DNS, not your internal DNS. Please do a nslookup from external to verify your MX record configuration. How to Use Nslookup to Verify MX record configuration http://technet.microsoft.com/en-us/library/aa998082(EXCHG.65).aspx Below is the process of Exchange receives an email. 1. The sending SMTP server queries DNS to locate the IP address of the recipient's SMTP mail server. 2. The sending SMTP server then initiates a conversation on the recipient's SMTP server (on port 25). On an Exchange gateway, the recipient's SMTP server is the SMTP virtual server that is configured to accept inbound Internet mail. 3. Ideally, the inbound SMTP server only accepts the incoming message if it is destined for a recipient of its SMTP mail domain. These recipients are defined in the recipient policies (unless the server is open to relay, which is strongly discouraged). 4. When the message is accepted, the SMTP virtual server uses the transport mechanisms within Exchange to determine the method for delivering the message. Exchange locates the recipient in Active Directory and determines which server in the Exchange organization will deliver the message. 5. Finally, the SMTP virtual server uses its internal transport mechanisms to deliver the message to the appropriate Exchange server. Related article: http://technet.microsoft.com/en-us/library/aa996068(EXCHG.65).aspx Thanks, Elvis