I'm trying to set up an integration with a help desk system that allows for us to automatically assign it to certain queues by either parsing the subject header or if it comes from a specific address.
Ideally I'd like people to be able to email a specific address and then this get forwarded to the helpdesk system's email address which can then add it to a specific queue.
However, I can't seem to find a way to both preserve the original sender (so the original user can be directly contacted and assigned to the ticket) and change the subject to add something that can be parsed by the system.
Using Gmail's auto forwarder will preserve the sender but I have no control of the subject header (or anything actually). Using Apps Script or IFTTT I can change the subject of the email and then forward it on to the right email address but then the email will be sent from the forwarding address rather than the original sender.
Is there a way to preserve the original sender's address but change the subject header? I was half hoping that I could fake the
from: header using Apps Script but that doesn't appear to be possible other than from aliases of the Gmail account.