@gobenizzle unfortunately, no. I was just re-reading this thread. What is your use case for this (sorry, if I missed this).
@tamayers you said use case is "A reason for this (such as my use case) is that you might have inboxes for employees using Google Workplace, Microsoft Exchange, or Cloudron email for user account and then support inboxes for customer inquires or sales that you do not want handled on the same system." I am not sure why this is done, is this to save money because exchange/workspace charges per mailbox?