I have a Flow whose trigger is When a new email arrives in a shared mailbox (V2). This is operating against a shared O365 mailbox. For each new email, this flow creates an item in a SharePoint list, while enriching that item with certain additional values fetched from another endpoint. In effect, this allows the mailbox owner to use SharePoint to search the mailbox based on attributes not actually present in the original emails. This flow works fine.
But there is a lot of existing email -- that is, emails created before the flow was created -- that I also need to get into that list. I don't see a way to do this short of writing a lot of node or Java to grab the old emails through Graph or REST, and populate the list through REST. There doesn't appear to be a way to write a flow to open a shared mailbox and act on certain existing records in the Inbox.