12268 PHP Snippet for email sending

What im looking to do: My members subscribed to my mailing list... I have an option to send them a newsletter, but dont want to flood my server doing it. I want to be asked How many should be sent at 1 time ... Lets say 25 at a time. After those 25 have been sent, a link to click, to send the next 25 (or whatever I define) ... Emails are stored in SQL DB. Need someone to make the base snippet for me, and I will add it into my own program. Many thanks.