This is a very simple one, but one that can take a lot of google-search-query-nuance tweaking to find.
It’s easy to find the documentation to do PayPal Express Checkout, but to find that one little field where you send an alternate user as the recipient of the payments, well that’s downright impossible. It is not in the docs (at least not as of this writing 5-18-2011).
How simple is it? Very — the variable is “SUBJECT”
Yes, you specify an alternate “SUBJECT” of the transaction.
Normally your SetExpressCheckout request looks something like:
Now it will look like this:
Payee_PayPal_Account is the email address/username the user uses to log in.
Hope this helps! Took us valuable time to find …