A physical postcard:

https://www.reddit.com/r/mildlyinteresting/comments/utgukp/i...

I've never gotten an unsolicited e-mail ad from DDG. And for every half-serious company which does send unsolicited e-mail ads, at least I know I'm the one who gave them my e-mail address. If people are getting e-mail ads from Brave without ever having disclosed their e-mail address to Brave, that's seriously concerning.

Snail mail.

Sending unsolicited e-mail advertisements are explicitly illegal in my country and companies that do that could loose the right to exist.

It should also be mentioned that using private information for unsolicited advertisements is something which is likely in conflict with GDPR.