PayPal does allow the "+" suffix for the user part, so you could do [email protected] and the mails they send will end up at [email protected] (it's part of RFC 2822, and it works for Yahoo, GMail (I've tried both), apparently outlook.com, and maybe others: https://www.ghacks.net/2013/09/17/can-now-use-email-aliases-... ).

When I moved countries, PayPal didn't let me change my country of residency, so now I have a user+[2 letter country code]@domain for the PayPal account in the new country. For IKEA it was a bit more silly because they seem to have several customer-facing systems, and 1 system worked fine but another didn't like this concept (I couldn't log in)...