Most of my email is on my own server, but in my experience (with gmail, etc.) marking a sender as spam will keep them out of my inbox going forward. I would per

Most of my email is on my own server, but in my experience (with gmail, etc.) marking a sender as spam will keep them out of my inbox going forward. I would personally filter the email, but for those who don't understand that process, marking as spam can be effective as well.