Is it possible to use gradients on elements in newsletter emails, using CSS? Is the full property supported?
In short, no.
Email clients very rarely support HTML5 or CSS3, and so it will break in any clients that don't.
You could always have a fallback, but the load time won't change too much, and adding CSS3 simply adds more code to keep track of.
I would recommend using image tags and hosting the images on your server, and that's if you really have to use gradients at all.
With email, generally the simpler the better. Personally, I prefer recieving plain text.
FWIW, here's my go-to resource for CSS support in email: https://www.campaignmonitor.com/css/
It doesn't have specific info for background gradients, and since this falls under the background-image property. My hunch would be that there's inconsistent, if any, support amongst email clients as it is a fairly feature to CSS. My only hesitation is that I think a background gradient is treated as background-image, which seems to have decent support except for Outlook.
来源：https://stackoverflow.com/questions/13955814/is-it-possible-to-use-gradients-in-emails