I thought some would find this interesting and useful...
Here's where you can find all kinds of mailing lists to rent... Including for physical mail, email lists*, and phone lists...
There are many different categories, such as stamp collectors, business opportunity seekers, healthy recipe buyers, cryptocurrency investors, golf enthusaists, etc.
You can also see how large the lists are, too!
Mailing List Finder
https://lists.nextmark.com
Fascinating stuff...
Dien
* To my understanding, to be legally compliant, you don't send the
emails to a rented
email list yourself. Instead, the list owner will send the emails out from their own email address... Doing it otherwise would violate the law, as the email subscriber subscribed to receive email from one specific entity... The law is different for physical mail.