It is generally bad practice to use <div>
elements when working with HTML E-mails. You should refer to strictly using <table>
layout instead to get your desired results. The reason for this is that many E-mail clients simply don’t support anything else. Other than that, some E-mail clients will also ignore inline padding and margin styling on <img>
elements, as well as some other specific stuff. It really all depends. Rule of thumb is, as long as you use a <table>
layout, you’re probably fine. For the most part anyways.
This old article covers some of the inconveniences with the <div>
element in HTML E-mails.
Alternatively, check out this article on Outlook 2016 HTML E-mail tips.
I would also highly recommend navigating through this gem of a post if you’re interested in learning more about HTML E-mails.