How to get Contact ID from selected Contact in Form of sending mail?

Hello everyone,
I have been trying to find a way to add a contact to a PO when you send an E-Mail from the PO and the Receiver is still not in the Contacts of the PO.

To be clear: when I select the red circled E-Mail I also want to get the ID of that contact since I need it to add the contact to the PO.
Thanks in advance

Go to CRM, go to vendor, go to contacts.