Making sure your email is marked as spam
We usually want people to get our emails. We set up DNS records for SPF and DKIM, so domains are not marked as spammy. We care about the IPs we use to send emails since that can make a difference too!
To be honest, I never thought about making sure my emails were marked as spam. This quasi satirical website, Straight to Spam, can help you with that.
(The trick is to include all the wrong, in this case, the right, keywords in your message.)