Op said "sent a message to a friend", it made no reference to facebook
Gmail famously scans the user emails to sell the info to third parties and sell adds
Ought be noted that while WhatsApp to my knowledgeable doesn't carry such a clause. It would be idiotic beyond belief to be led to believe that Facebook doesn't do the exact same thing
Do you have evidence that they do? I think Google said they did this a long time ago, but they stopped since email content didn't actually improve revenue on those ads. Message data just isn't very helpful for ads, they would do it if it was useful but it isn't so they don't.
Gmail famously scans the user emails to sell the info to third parties and sell adds
Ought be noted that while WhatsApp to my knowledgeable doesn't carry such a clause. It would be idiotic beyond belief to be led to believe that Facebook doesn't do the exact same thing