> how does URL-rewriting benefit Google in this situation? When I use, say, thunderbird, Google does not know whether I opened an email, interacted with links

> how does URL-rewriting benefit Google in this situation? When I use, say, thunderbird, Google does not know whether I opened an email, interacted with links on them or downloaded images/external resources in them. With link-rewriting, when I click on e.g. shopping.example.com/product/1337 and not on shopping.example.com/product/42 in an email, google now knows that "berkes, thunderbird-user is more likely to like product 1337" and can offer that data to advertisers.