If you like man trivia (and why else would you be reading this?) you could check out the top comment at https://unix.stackexchange.com/questions/405783/why-does-man...

(discussed at https://news.ycombinator.com/item?id=27994194)

I use Fastmail with my own domain and 1Password. Together they give me a “masked email” button for forms that generates a random enough email address (two common words and four digits) and records the domain it was for. You can also create them ad-hoc from Fastmail’s interface.

As well as simply attributing leaks, it’s most valuable as a phishing filter. Why would my bank ever email an address I only used to trial dog food delivery?