Well, thinking about it, what you could do, is set the temp folder to the UNC path to your exchange server -
and then create the batch job to run this script on the exchange server
FOR /F "tokens=*" %%G IN ('dir /b C:\inetpub\mailroot\dynapickup\*.tmp') DO c:\windows\system32\ReplaceText "%%G" text/plain text/html
move *.tmp c:\inetpub\mailroot\pickup
And you wouldn't need to fill in drop folder info.
This assumes that IIS is installed on the server. If not, the then the folder structure would have to be created manually.