There are two requirements for this , most articles do not mention the second requirement.
1. In the ASP configuration set " Send error to browser" to true
You can also do it using the the command-line tool AppCmd.exe
appcmd.exe set config "Default Web Site" -section:system.webServer/asp /scriptErrorSentToBrowser:"True"
http://www.iis.net/learn/application-frameworks/running-classic-asp-applications-on-iis-7-and-iis-8/classic-asp-script-error-messages-no-longer-shown-in-web-browser-by-default
2. In the Error pages Configuration go to " Edit Feature Settings" on the right & select " Detailed Errors"
http://stackoverflow.com/questions/2640526/detailed-500-error-message-asp-iis-7-5
Note this applies to all errors.
a3d18495-a1c0-459d-890b-9d72143f4781|2|5.0
When you install SMTP on Windows 2008 Server , SMTP logs may not be getting generated. Websites may or may not be sending out emails & when you click on Current sessions in IIS 6.0 manger you get the message " No such interface supported".
While not obvious the ODBC Logging module a role service in Server Manager needs to be installed.
Windows Server 2008 SMTP Service logging
http://www.iislogs.com/steveschofield/windows-server-2008-smtp-service-logging-tip
Thank you Steve Schofield
still does not work then try this.
Close MMC
C:\Windows\System32\inetsrv>regsvr32 smtpsnap.dll
C:\Windows\System32\inetsrv>regsvr32 smtpadm.dll
Reopen mmc
Thanks UnderCoverGuy
affea240-5348-403f-865b-d496fd8166b0|4|5.0
When you build a website in ASP.NET on IIS 7.0 parts of your website may not work & display the error shown below.
In this instance the website is sending an order confirmation email.
The reason you get this error is that the default configuration of IIS 7.0 uses the user MACHINE NAME\Network Service to execute some types of anonymous access and not IUSR_MACHINENAME.
You have two options one is to setup impersonation by editing the web.config file if you are just the system admin & are uncomfortable messing around with the web.config file then the simpler option is to give the user MACHINE NAME\Network Service modify rights the folder in question which in this case is C:\inetpub\mailroot\Pickup\

Server Error in '/' Application.
Access to the path 'C:\inetpub\mailroot\Pickup\b47ff1f1-dc5a-4fed-a8c2-a80d7c26d901.eml' is denied.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.UnauthorizedAccessException: Access to the path 'C:\inetpub\mailroot\Pickup\b47ff1f1-dc5a-4fed-a8c2-a80d7c26d901.eml' is denied.
ASP.NET is not authorized to access the requested resource. Consider granting access rights to the resource to the ASP.NET request identity. ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS 5 or Network Service on IIS 6) that is used if the application is not impersonating. If the application is impersonating via <identity impersonate="true"/>, the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user.
To grant ASP.NET access to a file, right-click the file in Explorer, choose "Properties" and select the Security tab. Click "Add" to add the appropriate user or group. Highlight the ASP.NET account, and check the boxes for the desired access.
Source Error:
If it helped would appreciate a rating star.
Ashwin
Lansend.com
Microsoft Certified Partner
Version Information: Microsoft .NET Framework Version:2.0.50727.3615; ASP.NET Version:2.0.50727.3618
ae52aac2-2719-45a0-8892-32038798f515|4|5.0