I don't offer a free service, just a $12 a year fee based service. I deliberated about the banners, then decided to put them in too as I'd seen it done on another site ("we use a combination of fees and advertising to offer you a quality service"). Having had a quick think about a free-to-fee service it should be easy to implement. Depending on your credit card provider (I use WorldPay) you would just pass the username and relevant info onto the payment page, so users could click a link to upgrade at any time.

It's not fully automated, but then I'm not Yahoo so manual processing isn't a chore (yet). I have a general 'Email Service' folder, with subfolders: 'AWAITING check payment' and 'PAID by credit card'; with subfolders in both of them: 'PAID by check' and 'Problems with credit card' respectively.


Regards

Jason