When I try to file an email from the FYI drawer in Outlook I see the following error message in drawer
"Message inaccessible due to invalid credentials, please re-login from web application and try again"
You are logged in to the FYI Add-in to a different account to that of the recipient of the email. It is likely you are using two different email addresses.
Due to Microsoft limitations, you cannot use the Add-in technology that FYI relies on for AutoFile. Refer to the Microsoft article Create a shared mailbox.
You can create a separate Outlook profile for the the email address.
Open the shared mailbox from the web version of Outlook to use the full potential of the FYI Add-in. Refer to How can I use a Shared Mailbox?.