First off all, this isn't for spam, its to send out a newsletter to subscribed users. Second, you don't even know what you are talking about, being that you didn't answer the question at all. Third, if you got nothing good to say, don't say anything at all.
Anyways, putting the drama aside, here is my question simplified:
I have about 350 subscribed users, I make a email form, put in my message, and hit send, how can I make it so that the mailer only mails to 25 users at a time, so the server load doesn't shoot up and break through the roof.
I hope y'all can understand better now. Really need help on this, thanks.