Individual emails are either Ham or Spam. Ham emails are non-Spam. There is no inbetween. It’s just a matter of where the inbox places the email. Spam or Inbox.
But you can send the same message from the same email address to 5 different people (we call that 5 emails) and 2 might be ham while 3 are spam. Or 4 or ham. Or all are Spam.
That is to say, you never really know until the message hits the inbox.
It’s all driven by Artificial Intelligence (AI). It sounds complicated, but it’s not. Conceptually AI is very straightforward.
You know those little “I’m not a robot” challenges that Google makes you do where you click on the cars and traffic lights to prove that you’re human? Google’s using you to teach AI (specifically driverless car AI) what traffic lights and people look like.
AI learns by being shown a ton of examples of what is and what isn’t a traffic light and then doing some crazy math and coming up with a magic formula (literally a black box equation) that can figure out whether or not new examples are or are not a traffic light.
Spam filters are AI. Spam filters look a billion samples per day (all of the emails we send) and then use human annotations (our spam reports) to train themselves what is and isn’t spam. Until they sort of just magically know.
Which means that if we want to stay off the spam filters, we have to know how to send emails that don’t look like spam to the people that read them so they don’t mark it as spam.
Seriously. It’s as simple as that. If your recipients don’t think your mail is spam, neither will the spam filters.
And the spam filters pay attention to more than just the content of a message. They pay attention to your email address, your ip address, and anything else that identifies you as an individual email sender so it can use your sending history to judge whether or not your emails are spam.
This history of data that the AI uses to decide whether or not you are likely to be sending spam is called your “Reputation.”