> Providing expiration notification emails means that we have to _retain millions of email addresses_ connected to issuance records. As an organization that _values privacy_, removing this requirement is important to us.
A mailing list. Is still retaining emails somewhere. Doesn’t matter if it’s stored in a text file on a usb drive in a vault. It’s still retaining an email list.
You are talking of a volume of around 600 000 000 domains (based on a plot on their website) that try to renew at best after 8 weeks. And that's just default profile, there are 160h certs profiles now [0].
You think they will ever send nearly as much as (at least) 75 million newsletter mails weekly? Sendgrid's highest value in their pricing slider is 1,25 mil a week.
Are you really questioning a free SSL Certificate system when it says something is too complex and not worth it?
If you ever set up a free SSL before LetsEncrypt, you'd know they're amazing and you can trust them not to lie to you, especially about this where they've outlined the reasons clearly.