I have the same requirement - will appreciate a lot if you can help in anyway.
We are using Pega 7.1.9.
I cannot send the mail to gmail due to project restrictions.
However I have selected the option 'Save original email (in EML format)' from the Email Listener.Now when I decrypt the bytecode from pyAttachment page I can see Email Headers like Message-ID.I guess it means that the headers are coming to the mailbox and the email listener can read it.
But is there any OOTB way to parse it and populate it in the properties ?