They then told their email provider that the email they requested was spam.
I've considered putting up a page with a list of these peoples email addresses, but I feel like it would end up causing me more problems than it's worth.
[edit] There should be a system where I can prove to an email provider that I was in fact given permission to send to an address (for a period of time, and/or for a specific quantity of messages). If there was a standard email header where you could stick a callback URL like:
Request-Permission: url=https://www.example.com/callback period=1D count=10
Once pressed, it would replace the “spam” UI element with “unsubscribe”.
Yes. It’s clear that you have no intention to reach them afterwards. But to them it is not so clear, and they mark these innocent letters as spam preventively, out of habit, cause other sites committed abuse in the past and they don’t want to test yet another service’s good nature. Much easier to ban you forever and forget about that, even before you did something unexpected. I know it’s unfair, and I don’t act like that, but they can and some of them do. No time on their hands to differentiate. Modern email culture is rotten to the core and popular email services only cultivate that.
Then they will go into their email client and click the spam button on both of the emails that I sent them. The confirmation email, and also the test email.
Even though they requested these emails. Even though both emails have an unsubscribe header and link which takes them to a place where they can opt-out in perpetuity from receiving any further email from me.
I know this, because I get feedback loop emails when people do it.
This happens regularly.