I am new to Paypal and have previously build an invoicing application for the company I work for and wish to send a link on the invoice where they can pay their bill, how wo
https://www.paypal.com/cgi-bin/webscr?cmd=_xclick&business=the-recipient@email.here&amount=0.99&item_name=99%20problems%20but%20this%20invoice%ain't%20one
Additional parameters you can specify in the GET are listed on https://www.x.com/developers/paypal/documentation-tools/paypal-payments-standard/integration-guide/formbasics
Note: The amount would be plainly visible in the link. If you want to make it that little bit more secure, I would highly recommend looking into the BMCreateButton API call.