An academic email address seems to be a magnet for all kinds of spam, and while some of it is obvious grift, some is from otherwise legitimate companies. They will even often include an "unsubscribe" link, suggesting the onus is on the receiver to do so.
This question asks about whether one can find out how those companies got your email address and whether you can ask them to stop mailing you, both answered in the affirmative. This seems like too little, too late—surely, these companies should not be mailing me in the first place?
Is there any course of action I can take that may have further consequences for them?
My question is primarily written from an EU/GDPR perspective, but answers for companies or recipients in other jurisdictions are bound to be useful to someone, too.