Content based filtering is a GIANT topic. And something to take into account when we’re talking about deliverability. So we’ll give you the quick and dirty on what you need to know as it relates to email marketing.

Content based filters look at a wide range of things:

* The actual text in the message
* The domains (and IP addresses) of the domains included in the message (are you including links to sites that have bad reputations?)
* The hidden structure of an email (coding)
* What’s in the body of the message (is it a giant image with a small amount of text? – avoid that)

There really isn’t a single bit of your message that content filters don’t look at.