Marie wants to know an alternative to Gmail. Leo stopped using Gmail because of their invasive ads, but the other side of the coin is that Gmail has the best spam filters of all. Leo moved to FastMail, so Marie can use Gmail to initially filter her emails, and then forward the rest to FastMail. Then she can run the secondary SPAM Sieve there.
Marie is also concerned with Facebook. Every time she does a search, an ad appears on Facebook for it. How does that happen? Leo says that probably wasn't Marie's search, so much as her going to a website that has Facebook icons, and it reads the cookie the website put in her browser. So technically, Facebook isn't spying on her: they're getting metadata from the website she visited.