Return from PayPal

I am in the process of setting up Zen Cart to use with PayPal. I have only one product and one price which includes shipping but not sales tax. I am currently using PayPal, however, if you set it up with Auto Return 'ON' and PayPal 'OPTIONAL' the purchaser will not automatically be returned to the 'Thank You' page. I need to have this happen unconditionally for reasons of tracking sales. If anyone has been down this road before I'd like to hear how you set it up.

I'm not aware of any workaround for that if you're using IPN/Website Payments Standard.
If the customer doesn't have an account, then they will be asked whether they want to create one or not. And until they make a choice, nothing else happens.

Unless you use Express Checkout ... in which case the payment process completes regardless of whether they had an account or not at PayPal.

Thanks! Perhaps I'll look into Express Checkout if that will get me back to the thank you page without the customer's intervention.