Send email to all registered users [closed]

Question

I've got a about 60 registered users. How can I send an email out to all of them? Any suggestions on how to achieve this. The users have registered, so I don't think they are going to mind an email send to them, but how could I get that to work? would a plug in do what you said? send an email out to the registered users? or should I install a newsletter plug in and get everyone to sign up to that again/separately? I'm not looking for specific plug in names (although that would be handy) more how it works in theory?