How to identify which of my users sent me money via paypal.me?

[rotopi]

I have a subscription site and send paypal.me links to some site users.
So on my site I have the user site email address.

Now when someone pays, I see on PayPal his name and his PayPal email address.

But if this person registered on my site with a different email and some mickey mouse nickname?

I do not see any way to synchronize the person who paid me to the person who is registered on my site !!

Of course I can send email to the email address from PayPal and ask him what email he used on my site, but this requires to wait for his response and risk a dispute if he didn't get or didn't see (spam folder for example) my email. Not to mention that it takes time efforts better spent some place else.

Any idea how to synchronize paypal.me and my site?

I was looking for an option like paypal.me/xyz/amount/<my_info>

and somehow see <my_info> on the transaction and/or via api

This way I can automate the flow so when someone pays, the system automatically opens his subscription

Any idea?

[Quandary · Accepted solution]

You may also want to visit the Developer community for possible suggestions.

[rotopi]

Thanks. It seems that paypal.me does not support (at this tage) passing a parameter. So it requires the merchant to work hard to make it work and synchronize somehow (there's no good way to do it) between payer email on PayPal and user email on your site.

The solution I found is the third option mentioned here: 

Third option is the rarely advertised custom cart URL. I don't have anything that details this however the following sample link can get you started.https://secure.paypal.com/xclick/business=EMAIL%40DOMAIN.COM&item_name=Cart_Invoice_Custom_Name&amou...

which has all the options needed (like disable shipping address, return url, notification etc) and the user sees the familiar PayPal payment page instead of the new paypal.me page

[Whac-A-Mole]

apply for a merchant account and skip Paypal