Stack Overflow’s reach, we strive to support email clients with low levels of HTML &amp; CSS support (namely Microsoft Outlook, a <a href="https://emails.hteumeuleu.com/trying-to-make-sense-of-gmail-css-support-after-the-2016-update-53c15151063a" target="_blank">few versions of Gmail</a>, and a handful of <a href="https://emails.hteumeuleu.com/should-we-stop-inlining-styles-in-emails-8c3b64f0d407" target="_blank">mostly non-US clients</a>). Less than 1% of a mailing list can still mean a few thousand user