You know what's sucky about regular sending newsletters to customers in a campaign? You need an available email list before sending anyway and if you don't have one, you will be struggled! Don’t be worried! We have solved this problem very well with SendGrid Integrate add-on.
By installing this add-on, everytime there is a new user registered into your forum, it will be delivered automatically to the SendGrid subcriber list. So in the next campaign, your mission is only press Send button without thinking in making email list.