That seems like a unique requirement and I'm not aware of a way you could accomplish this. Perhaps if you provide more details about the bigger picture of the process we can provide some alternatives or further input.
We have a bulk load with csv which create Pega case. In between bulk load need to Verify one Inbox and check the Email body for some business details.
if details are there need to trigger service for more details .
Impl : There is File listener which load data and create case. Before landing to assignment I have one utility shape with activity where I want to add the Email body reading functionality.
There are some more business functionality i have with that Utility activity that's the reason I am looking implementation with activity. If it possible to read in that activity it's good.
I have not seen an email listener used in this way in Pega and as far as I know it's not possible using out of the box features. The email listener will always be on (assuming there are no errors), checking for new emails periodically. It sounds like you would also like to search through the inbox for specific emails that correspond to the cases be created from the bulk load, which again is not possible as far as I know using out of the box features.
Would it be possible to do this in the opposite way? Meaning have cases be created based on the incoming emails, then when you are bulk loading you can check the work object data in the database rather than checking email in an inbox?