How to send email directly to IDR mailbox without oracle business unit id on the subject line?

Summary:

Is there another option to send invoices into Oracle other than using the 15 digit code in the subject line.? The overall goal is to have vendors send invoices to an email address and have them automatically routed into Oracle but we cannot ask all our vendors to add in a 15 digit code in the subject line. 

Content (please ensure you mask any confidential information):

We use IDR for invoice images to be imported to Oracle AP. Ours was oracle upgrading directly to IDR since our implementation was from 2020. So we had been sending emails to IDR mailbox with _BU id as subject line to route the document correctly to the correct BU. Our invoices are sent by vendors to a generic mailbox and our AP processors emails it to IDR email by appending the subject line. Is there a way for us to give the IDR email address directly to the vendor so that invoices go directly to the IDR queue. We