I have been doing some investigation about how you could serve a different image on desktop than a mobile.

It seems that this can be achieved with with a media query and the breakpoint is 325px? You would then have 2 JPEGS. 1 for mobile and 1 desktop. If the width is above 325 you get desktop, below you get mobile.

Does anyone have any example emails/code that they could share so I can see how this would look/work?

Thanks for all your help.