Hi Tim,
Try using the base tag in the HTML header tag.
Then place image in /webroot/ui/evolution2/images folder and the below script should send an email with an image .
I have hardcoded the URL here for simple and better understanding.
<gel:script xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:core="jelly:core"
xmlns:file="jelly:com.niku.union.gel.FileTagLibrary"
xmlns:gel="jelly:com.niku.union.gel.GELTagLibrary"
xmlns:mail="jelly:email" xmlns:sql="jelly:sql"
xmlns:util="jelly:util"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<gel:email from="dummy@dummy.com" subject="Test"
to="anotherdummy@dummy.com">
<![CDATA[
<html>
<head>
<base href="SCHEDULER URL HERE/niku/ui/images/" target="_blank">
</head>
<body>
<font face="Arial">
<font size="55">
<I>Hello</I> <br>
<img src="SO.png">
</font>
</font>
</body>
</html>
]]></gel:email>
</gel:script>
Hope it helps.
Regards
Nitin