Sidenote, but I find this post maddening to understand, because the author seems to be using the word "e-mail" to mean both "e-mail address" and "e-mail message", and then uses ambiguous pronouns to boot:

> In conclusion, if you only use emails for transactional emails, you might be able to only store hashed versions of them.

HUH?

The most obvious way to interpret this sentence is as storing hashed versions of transaction e-mail messages. Which makes no sense and isn't what the author means, but wow this is some confusing writing.