Anything related to the delivery will be stored in nms:delivery schema. If you used AEM content then you need to write QueryDef to read actual content Id that was synchronized with the delivery and then find it in AEM.
var emailText= delivery.content.text.source.toString();
var emailHTML= delivery.content.html.source.toString();
It will give you XML structure of your email. You can fetch whatever data you want to fetch, like you want to get URL of your HTML you can use:
var url= delivery.content.text.urlConfig.url ;
Thanks Jyoti for the info.
Tried above code but its not giving value of source.
Hence changed code to <node expr="[content/sms/@source"] alias="@content"/> and its throwing below error:
How can retrieve source data.