Convert my PC to be relay smtp

I need to convert my PC to send emails, not from the built in localhost. I heard about hmailserver, that can do this task, so if you can configure it to work will be good for me. Whatever you will use I'll need to have my own SMTP server on my PC to send any count of emails / day with 0 cost. My PC specifications: - I7 Processor - Win 7 32bit - dynamic IP from the internet provider I am not sure if port 25 is blocked from my internet provider or not.