However, as email marketing developed as an effective means of direct communication, in the 1990s, users increasingly began referring to it as "spam", and began blocking out content from emails with filters and blocking programs. In order to effectively communicate a message through email, marketers had to develop a way of pushing content through to the end user, without being cut out by automatic filters and spam removing software.
Please forgive me if I missed this in some of the comments and replies, but I saw nothing on Infusionsoft or Marketo. I was expecting to see both in your analysis, but nothing was mentioned, save for the remark early on that Active Campaign has rocketed past Infusionsoft in the marketplace. Is it because you consider them outside the “Email Marketing” space which was the subject of your analysis?
Email design matters in any successful email marketing campaign. If your emails look terrible, that reflects badly on you, and can make people stop reading. With more people than ever reading emails on mobile devices, it’s important to use a responsive email template so your email resizes automatically whether people are reading it on a phone, tablet, or desktop.