99% of the people who tell you they wouldn’t use the product unless it can’t read your email wouldn’t actually use it regardless, and are just asking for things they don’t really have any intention of using.
edit: I just wanted to add I think it's kind of a dick move on pg's part to ask someone to build this when there are like four different versions that already exist. If you like those products then you should promote them, and if you don't like them then you should email the creators with feedback. Asking folks to build additional competing products without doing that first is poor form, as is asking people to build stuff that you don't actually care enough about to Google to see if it already exists. I don't mean to pick on pg specifically, I just see this kind of behavior on Twitter (and HN) all the time, often from startup investors, and I think it deserves to be called out.
Separate the wheat from the chaff.
That probably doesn't work for physical products.
If not, what happens if someone else releases a superior product in the interim? Or my business needs change?
They'll get your business.
> Or my business needs change?
I didn't waste my time building you a feature you won't pay for.