Sure, sending spam that I can opt out of isn't the worst thing they can do. But if you are selling security products I expect better morals than that. This is yubico squandering trust in exchange for sending a few more marketing emails.
Considering legislation: I live in Germany. Over here unsolicited marketing mail (snail mail) addressed to me is illegal. I fully support legislation that extends the same standard to email (and I'm pretty sure yubico's behaviour is illegal here). It's waisting my time and computing resources for somebody else's gain (and that on a massive scale: if you waste just one minute each from a million people, that's two full years wasted)
Considering legislation: I live in Germany. Over here unsolicited marketing mail (snail mail) addressed to me is illegal. I fully support legislation that extends the same standard to email (and I'm pretty sure yubico's behaviour is illegal here). It's waisting my time and computing resources for somebody else's gain (and that on a massive scale: if you waste just one minute each from a million people, that's two full years wasted)