If a user updates his email address - and then pays through the same gateway as before - to prolong his account - the old email address will be used there. This is wrong and leads to invoices not arriving or similar.
While the email address should not be changed for ongoing subscriptions - for a new payment the new email should be used - not the old. Often users don’t even have access to the old email anymore. Stripe/paypal integrations like invoices need to have the new address.
Hi Felix.
Thanks for the insight. So this is for single (buy-now) payments, right?
The Stripe integration is picking up the Stripe customer ID from the user’s profile and just going with that, so I’ll look at how to update the email address there…
And what PayPal service are you using? Standard, Express Checkout, Pro…
Thanks! 
Yes buy now or new subscription on PayPal button payment or stripe proform with logged in user.
I’m not sure about the problem why someone who updated his email in account, and also uses the new address at PayPal, still receives invoices at the old email, might be a fault in my invoice plugin or at quaderno.io too. For stripe I’m pretty sure the fault is in s2member however.