We host several web sites that need to send out emails (info@domainname.com or Support@domainname.com) We have created a Windows Server 2008R2 Server for SMTP Relay to forward these messages. Relay is restricted to access from our DMZ by way of Firewall Rules in our SonicWall. We have two separate virtual Web Servers, on the same host machine, in the same domain, in the same subnet. One of the two machines can telnet to port 25 of the SMTP relay server. The second web server "Connect Failed"; "Could not open connection to the Host". This happens whether or not the windows firewall on Web Server #2 is disabled or not. There is no AV on this machine. The SonicWall firewall rules for the two Web Servers are identical except for their referring IP addresses. I am at a loss. Thanks for any help you can provide, Mark

Hi, Can you ping your relay server from the client machine and can you ping your DNS from the relay machine. When i say ping i mean ping the name not the IP? Martin If you find my information useful, please rate it. :-)

Hello, You have to check which port is used for sending mails from your Web sites. If it is port 25 then it should be available for both computers. You can PortQryUI or PortQry V2 to check that it is opened. If it is blocked, you have to determine which network component is blocking such traffic since you have no AV. Please also check that DNS resolution is made correctly if you Web servers use the FQDN of the SMTP relay for sending mails. More if you ask your SMTP Relay solution Technical Support for assistance. This posting is provided "AS IS" with no warranties or guarantees , and confers no rights. Microsoft Student Partner 2010 / 2011 Microsoft Certified Professional Microsoft Certified Systems Administrator: Security Microsoft Certified Systems Engineer: Security Microsoft Certified Technology Specialist: Windows Server 2008 Active Directory, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Network Infrastructure, Configuration Microsoft Certified Technology Specialist: Windows Server 2008 Applications Infrastructure, Configuration Microsoft Certified Technology Specialist: Windows 7, Configuring Microsoft Certified Technology Specialist: Designing and Providing Volume Licensing Solutions to Large Organizations Microsoft Certified IT Professional: Enterprise Administrator Microsoft Certified IT Professional: Server Administrator Microsoft Certified Trainer

Make use of SMTPDiag tool. It helps you to troubleshooting the DNS resolution issues, further test the connection to the remote hosts and more. It DOES NOT need Exchange 2003, it only needs SMTP component. For more Information: http://msmvps.com/blogs/bernard/archive/2004/09/28/14480.aspx IIS and SMTP issues, it is better to discuss here. http://forums.iis.net/ Thanks

Raw approach to resolve: if you want to troubleshot this problem in fastest way and if it is possible to eliminate your firewall or another device which is coming in-between your web server and your SMTP relay, then eliminate it, if it resolved your problem then you need to add your elements like firewall in specific manner and see the behavior and then try to identify the problematic area. Else check the following 1. If your request is reaching SMTP server then check SMTP log file and see the exact status code served for the same request, if your request is coming to the server then server request status code will give you big clue. 2. Please check connection string of the application in your webserver, if it using Host name of SMTP relay then I will recommend you to bind the host name (SMTP) in system Host file \Windows\System32\drivers\etc\hosts ,This is to reduce the chance of host name resolution error. 3. In SMTP connection control Add web server IP address into accepted IP address as an exception. 4. Enable basic authentication and bind appropriate credential in application config file 5. Send SMTP message Limit and verify with the message sent. 6. Check SMTP security access list and verify that network services and local service. 7. error message is generic and it may be because of N number of problem ,so ask your Application team to generate verbose error log file. gud to use SMTPDiag as suggest by MYousufAl Thanks Ashok kumar

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