I run an email forwarding service[1] so I deal with spam a lot. Spam usually has bad formating, mixed charset, old/broken layoyt etc. Most of time, spam are o

I run an email forwarding service[1] so I deal with spam a lot. Spam usually has bad formating, mixed charset, old/broken layoyt etc. Most of time, spam are odd designs. Example they only have HTML and didn't have the corresponding plain text part. They have large pictures and too little text, they have many "invisible" part so that hide behind element to trick you to click the wrong thing. Even in plain-text, spam tend to include random links, very long text, weird chracter etc A nicely design, or a plain-text emails(only plain text) with nice format all are good signal of non-spam. In other word, consistency is signal of non-spam emails. But sometime marketing emails-which you never explicitly subscribe to, you just register for an account and got marketing emails, can also be consider spam, but from google/hotmail point of view they don't consider these are spam and that's reason they have Promotion tab to put thing in there --- [1] https://hanami.run https://hanami.run