> They admitted to have bought a list of addresses from another party where my email was part of the dump.
This is such a crappy practice for bootstrapping a new email marketing list, few things infuriate me as much as this. If nothing else, it instantly makes me never want to even look at your new product or service regardless of how good it might be.
I added the +coin name to my email when signing up for a crypto-related product years ago, have since seen that redistributed a dozen times for very obscure ICO projects.
unless you use high entropy aliases, there's nothing preventing someone from filtering out all the emails with "uncommon" domains for secondary examination. at that point, you can manually ascertain whether the email address is an alias or not.
john@example.com probably a legit address
bitcoin@example.com probably an alias
at that point you can either not send to that email, or if you're extra evil, try to frame another company (try sending to amazon@example.com or ethereum@example.com). it's not even that hard to do because 99.9% of people don't use custom email domains.
And even if a script could easily process addresses in an automated manner, it might be actively harmful to a marketer to do so. People who intentionally use disposable addresses are probably less likely to respond to email marketing and more likely to take actions against the marketer.
It's trivial to write that script, but not any more trivial than just generating lots of common_name@common_domain email addresses. Once you're willing to spam emails that didn't opt-in even to a list that you bought, you've entered into very shady territory.
This is such a crappy practice for bootstrapping a new email marketing list, few things infuriate me as much as this. If nothing else, it instantly makes me never want to even look at your new product or service regardless of how good it might be.