Yet, they state

https://policies.google.com/terms?hl=en

> Our automated systems analyze your content (including emails) to provide you personally relevant product features, such as customized search results, tailored advertising, and spam and malware detection. This analysis occurs as the content is sent, received, and when it is stored.

> "We will not scan or read your Gmail messages to show you ads."

that reads to me like ""We may do it for other purposes."

They obviously do, as does every mail provider that filters spam, at a bare minimum.

Whenever I book a flight google offers to set alarms and gives me don't forget your flight tomorrow notifications. They are obviously reading the email to achieve this.

Well, if they didn't you wouldn't be able to search in your inbox, among other things.

Interesting, looks like they stopped in 2017.