When writing SMTP extensions,
DLL is loaded by INTERNATINFO.EXE, but it is directly running this EXE.
You need to run Iisreset / Restart to start, but start IISRESET.EXE when starting.
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In this case, you must use Attach Process to debug
1. Select Attach to Process in Start Debug in the Build menu
2. Show System Processes
3. Additional DLL Add to write this DLL
5. Add to debug, set breakpoints, debugging
