I'm in control of what I put in my mouth too. Still don't buy the family size chocolate.

Perhaps you can, but maybe a compulsive eater lacks the self control.

I think this project is more for people who feel compelled to check their emails the second they receive them, but also find that doing so inhibits their productivity.

The lack of self control was why I don't buy the family size. I was making the same point you are.

I think they were saying they lack the self control to avoid buying the family size in the first place.

absolutely; however I confess to not actually be able to successfully implement that control.

I know of quite a few people who will actually exit their email app so no notifications can come in and they won't be tempted - suggesting there might be preexisting demand for this type of thing

Closing the e-mail app is the right way to go[0]. There's no need for it to be open when you're not reading/writing e-mails. The mail gets stored on a mail server anyway.

It's a funny thing. The habit of having your mail client open to get notifications sort of establishes itself in you, but it's very hard to kick. I've managed to do so, and I'm less stressed because of it.

[0] - on desktops. On mobile the equivalent would be to disable background syncing for the e-mail app.

Why not just configure fetchmail or your MUA to retrieve mails less frequently?

Because most people don't read email in this way. Sometimes I can't tell if some people on HN just live in a bubble or if it is actually just some attempt at superiority signalling...