Earlier quoted context omitted.
> The traditional way of doing this is to buy ads on fishing sites. Before digital advertising or Google reading emails to find out you're going on a fishing trip, how did people buy fishing equipment? Whatever we did then, we can probably go back to and be much better off. Like why do I need "relevant ads" on a blog about urban planning? What problem does that solve for me?
Google doesn't read emails for ad targeting.
I.e if I send you an email talking about finding a vacation deal to go to Egypt, we will get ads to that effect (obviously it'll vary somewhat).