I had to do a Server 2003 to 2008 OS upgrade this morning. Smartermail version is 11.7.5.  Hardware wasn't that old, they just still had server 2003 for the OS.  Anyway, after upgrade, IIS would not work.  Followed the instructions to configure IIS 7/7.5, and that got me most of the way there, but still wouldn't work.  Application log showed this error:

 

A request mapped to aspnet_isapi.dll was made within an application pool running in Integrated .NET mode.  Aspnet_isapi.dll can only be used when running in Classic .NET mode.  Please either specify preCondition="ISAPImode" on the handler mapping to make it run only in application pools running in Classic .NET mode, or move the application to another application pool running in Classic .NET mode in order to use this handler mapping.

 

I set Application Pools Managed Pipeline to CLASSIC, against the instructions which suggest INTEGRATED, but it did get the site up and running.

 

Is this going to cause further issues or can I leave it on Classic?