This is an advertisement.
Any company blog is boiled down to an advertisement at some level. If your interested in learning about how we technically do a lot of these things scroll to the bottom of the article and checkout the technical companion post. This post is merely gives context of what/why. http://hack.close.io/posts/building_better_email_integration... gives you the how.
EDIT: I don't know where I got my internet license. Wrong link now fixed.
2 time in this article you claim close.io got it better that everyone else. If you really wanted this article to be interesting you would have gone in depth without the "we better than other SaaS".
Instead you posted an overview that is not interesting to anyone