A workaround is to use a domain you own and either point it at one of those services or set up a catch-all address with your e-mail provider. I do the latter. I have @subdomain.adomainiown.example configured at FastMail with * delivered to a folder in my main e-mail account. As a nice bonus, I can also send messages with [email protected] as the From address when needed.
Since it is a domain I own and no one else uses it, no services will likely stop me from using it. And since it's a subdomain, it's not easy to discover so spammers can't indiscriminately blast away at [email protected].
What's nice with SG is that the emails are sent to /dev/null once the count is over whereas with a catchall, you keep receiving everything sent to any address for ever.
That's true, and I wish Fastmail had a better way of managing rules remotely (with something like remote sieve or an API) so I could script a click-button-turf-address-forever. On the other hand, I don't mind still getting the follow-ups for some stuff. For example, Target has [email protected] for years to use for order confirmations.