If it&#x27;s my own domain (probably not unusual among the HN crowd), I would sign up to e.g. kazinator.com by &#x27;inventing&#x27; an email address kazinator@mydomain.com, which is forwarded to my gmail through a catch-all email forwarding setup with my domain registrar. Emails to kazinator@mydomain.com now arrives to my gmail and hence it&#x27;s easy to block email (e.g. spam) arriving to this email address as well as knowing who leaked my email address to third parties.<p>As people have pointed out, it now seems possible to use the + functionality of gmail which I was not aware of, but the above setup avoids the issue of forms not accepting + in a valid email address.<p>This only works with a catch-all email forwarding as I mentioned, so if you want bounce on non-valid addresses it will not work, but like I said it has served me very well.