How to make an image responsive in email ad items
Making responsive email images
To make an image responsive, you need to edit the tag slightly at the end replacing the size with style="max-width:100%;height:auto;" which allows the image to reduce in size but not grow beyond the original size.
Example:
Original Tag
<!-- 728x90 email [email] -->
<a href="https://servedbyadbutler.com/go2/;ID=XXXXXX;size=728x90;setID=357745;uid=[EUID_HERE];click=CLICK_MACRO_PLACEHOLDER" target="_blank"><img src="https://servedbyadbutler.com/adserve/;ID=XXXXXX;size=728x90;setID=357745;type=img;uid=[EUID_HERE];" width="728" height="90"></a>
Edited Tag
<!-- 728x90 email [email] -->
<a href="https://servedbyadbutler.com/go2/;ID=XXXXXX;size=728x90;setID=357745;uid=[EUID_HERE];click=CLICK_MACRO_PLACEHOLDER" target="_blank"><img src="https://servedbyadbutler.com/adserve/;ID=XXXXXX;size=728x90;setID=357745;type=img;uid=[EUID_HERE];" style="max-width:100%;height:auto;"></a>