And how often. have you said stuff that you have not received advertising for? You will notice it when you get a positive match but not on a negative.
Data collecting companies can predict/rate your behavior for more then 20 years based. Since then. it has been perfected. They know that you are interested in those topics without having the need to waste resources on recording and analyzing every single audio stream.
You want the mail-crypt-plugin in dovecot.