Last few day, I was working on client server and found out their ASP.Net script do not able to send out any email from IIS SMTP.
After further check, it is found out port 25 is blocked from McAfee AntiVirus.
1. Locate the McAfee icon in your taskbar. Double-click the icon to launch the application. You can also run the program by clicking “Start > All Programs > McAfee > McAfee VirusScan.”
2 Click “Virus Scan Enterprise > Virus Scan Console.” Double-click “Virus Protection.” Click the “Access Protection” tab.
3 Check “Prevent mass mailing worms from sending mail.” This will disable port 25. Click “Apply” to save your settings, then click “OK.”