Are you allowed to inform paying customers that you are going to do this? This is my primary complaint here. I don't understand how this oversight happened. This is going to cause an enormous amount of time and energy to recover from this.
I can't be the only one who's basically completely blind to emails from major companies, including SaaS providers, because they're so fucking spammy that the SNR is like 1:99. Notifying me by email, for one of these places, is functionally the same as not notifying me at all.
[EDIT] Sorry, didn't mean to imply the parent wasn't paying attention, just that I'd fully expect a very high percentage of their users to miss the warning in all the noise even if they emailed everyone—even if they emailed them a couple times, actually. That's the cost of every company sending out tons of "join our online seminar on [product]!" and "hey, look, it's our newsletter you never read!" and "it's time for our weekly TOS modification!" emails.
This 1000x. I signed up for an SMS gateway service last year. Just for my own hobby use, nothing major. I gave them $10 to start service, and they charge like 2¢ or something per outgoing message.
They have like 180 different prices for 180 countries, territories, provinces, parishes, cantons, prefectures, etc. Every week one of those prices changes, and I get an email notifying me of that. I tried to turn those off in my preferences, but they refused. I can opt out of marketing, weekly digests, and "tips and tricks"; but I can't opt out of pricing notices.
So I added a rule on my end to hide those. I totally understand where they're coming from. They can't NOT give pricing change warnings. But at the same time, in the flood of constant notices, there may be something major I will miss.
It would be nice if they instead gave me the option to never spend more than $0.XX per message, and return an API error if an attempted send fails for price threshold violation. Then the spam wouldn't be needed.
The fact that the failure to send a single warning email to this particular customer wasn't both detected and considered a five alarm fire level bug under the circumstances is the thing that moved the decision to sunset the free tier from sad to disastrous for the user who posted the Tell HN in the first place.