There are strict laws on who you can send bulk email to. You could not just send bulk email to people who never posted, not unless you wanted to be on the wrong side of the law that is.
Under many countries including the UK Communications Act you can only send bulk email to people who have subscribed to receiving such communication from you, just because they have joined your forum doesn't mean you can send them bulk email. You also have to give people a way to unsubscribe and if you are a company you also need to include the company name and address within the email.
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Web Wiz NewsPad software can integrate with Web Wiz Forums to send eNewsletters to your forum members, but only those members who have checked a box in their forum profile to receive such communication from you. The sofwtare also handles unsubscribing.
Unfortunately at present there is not an option to send emails to those who have not posted, but you can select which forum groups, so if you selected the newbie group then these people would either have not posted or not posted very often. However, as I mentioned previously it will only send to those that have explicitly given permission to receive such communication from you.