Are you saying you send a request to an endpoint and a response comes back and the payload of the response is an email (say .html type so the content can be read by an xmlparser) or are you saying that an email is sent out to a specific mailbox and the content of the email includes a value you need to correlate?
Reason i ask is that if you just get a response with a payload as an email then thats workable (even if worst case the content type is just text/plain), but if theres some email generator that sends an email to a specific mailbox i think youre going to struggle to incorporate ReadyAPI! into your testing.
Need to know more details about your use case to gain a clear understanding of what you need to do before we can try and help out fella. Dedinitely need to know the datatypeof the response payload for the email which is revealed in the http headers
if this helped answer the post, could you please mark it as 'solved'? Also if you consider whether the title of your post is relevant? Perhaps if the post is solved, it might make sense to update the Subject header field of the post to something more descriptive? This will help people when searching for problems. Ta