tl;dr: related: Amazon sold (or gave) my secret Amazon email address to third parties without my express consent rather than using their remailers. I have exactly one email address that I use for Amazon, and I've never used it elsewhere for anything else. I occasionally receive emails from vendors (through the vendors' mail servers themselves, not remailed through Amazon per mail headers) at Amazon that I have bought…
This is why I use my entire domain as my email address (i.e. *@example.com is routed to my inbox). This makes it trivial to hand out a unique address every time I fill out a form.
If any spam arrives that is addressed to "vendor.com@example.com", it's obvious who sold their email db. Bonus: it's easy to filter out spam when the spammer is sending to a unique address.