The problem with these services (there also used to be one called hnnotify.com, which didn't last long) is that they're developed by HN users, who don't seem to care enough to keep the services working 100%.
YC seems to prefer a development model where the community fills in the gaps of missing functionality, but this also means you can't expect much from the resulting services. I would much rather have this built into HN.
I would prefer the best of both worlds - let users write plugins that consume a more robust version of the API and add that functionality themselves. They could even be posted publicly and integrated by other users with some arbitrary amount of karma, and plugins would necessarily be restricted in their capabilities and maybe even rate limited.
Heck, add an endpoint for a WASM compiler and an option to use multiple languages.
It will never happen, though.
I guess one of these HN-comment-e-mailing websites needs to apply to YC to actually have a chance of getting integrated into the site.
Same, I can see all sorts of nefarious uses for this service (not necessarily by the guy who built it, more so by trolls who can use it to target HN users). If I really need something like this, I'm competent enough to build and host it privately for my own use. Given I'm not even a programmer by trade, I'm sure that last statement is even more true for the majority of users here.
But until a feature like that exists, I'll stick with mine.
I have no intention on using the emails for anything but notifications from HNNotify. Included in that are: new features, account notifications, reply notifications, follower notifications (future).
Your email will never be used to solicit/sell anything 3rd party.