R – How are emails sent via Workflows in Microsoft CRM 4.0

I'm Creating a workflow that needs to send the users an email on set events. This I don't have a problem with. However can someone please confirm if you need the local windows SMTP service installed or if I can use another method for it to send the emails.

UPDATE
Ok I've just read about the E-mail Router, just need to find out where it is, and how to get to the configuration settings.

UPDATE

Update 2
Right, Iv'e looked into it and the e-mail router configuration is not used on this CRM set-up, it used an Outlook Add-in which I cant find a lot of into on.

However it appears to work flawlessly.
end update 2

Thanks