Fantastic claims about weight loss, pheromones, etc. Spammers frequently use bogus return addresses, to prevent recipients from complaining to them. Spammers pretend to allow people to have their names removed from mailing lists, but email to the addresses provided bounces. Some spammers have been demonstrated to use remove requests to build new mailing lists. Some spammers use security holes in mailservers run by innocent third parties to deliver their spam to avoid getting the inevitable negative responses.
Spammers actively attempt to get around recipient attempts to filter out ads.
Despite claiming that they don't wish to send ads to anyone who truly doesn't want to receive ads, the spammers hypocritically insist on sending spam to people who take steps to avoid it. There are direct and indirect measures that you can take to deal with spam. Getting their email accounts cancelled. Getting their websites closed down. For those of you using Microsoft Windows, there is a version of the software that you can download to your computer to run there.