PayPal IPN - Send a link to pay an amount?

I have a PayPal implementation using IPN and it works fine. However, in some cases, I will need to be able to send out an email to a user with a link to click on and 开发者_开发知识库pay an invoice amount. I'm not really sure how to do this - I know I can send them to a particular page on my site with query string variables - but what would the PP code look like to have the user see a button that says - "Pay X amount by clicking here".

After the user places the "order" they are supposed to pay. You should send them a link that is not overloaded with variables. Something like:

http://www.yoursite.com/PayInvoice.aspx?i=ENCODED_INVOICE_NUMBER

Then when they land on the invoice page. You can retrieve the information for their invoice from the "o" parameter in the query string. Load the invoice summary (list of products, etc...) and have button at the bottom/top saying "Pay Now".