When offered a choice, I always opt for plain-text email over HTML, “the way God and RFC 822 intended.” Most people choose otherwise. I contend that they chose poorly, and I am not alone in this belief:
So we decided to experiment with varying degrees of HTML-richness — plain HTML templates, snazzy and sleek HTML templates, beautiful headers, different sized and positioned images, various call-to-action buttons, and even GIFs — to see which would have the best result.
In every single A/B test, the simpler-designed email won. The emails with fewer HTML elements won with statistical significance.
To take this a step further:
HTML emails decreased open rates. What was interesting, however, was that not only were HTML emails receiving lower open rates than their plain-text counterparts, the more HTML-rich an email was, the lower its open rate.
Some of this may be due to mail filters. SquirrelMail, as implemented at my domain, blocks images it deems possibly unsafe, in which case your beautiful design looks like a game of Tetris that ended in a system freeze.
But regardless of the reason, it’s better without all those damn graphics. Trust me. Or God and that RFC.