I am not sure if I am posting to the right group but would like to ask about 'Failed to Validate the signature of the actionable message card' error that we are encountering with the shared account when trying to approve / reject SharePoint access requests within Outlook (app/web). For a while, it worked fine until recently. We do not encounter this issue with standalone user account. Is this a known issue for the out of the box feature or is something not configured correctly on our end in Exchange?
@Chris Ficek this started happening to me too in the last 2 to 3 months but only when I send the access email to my SharePoint group mail. There I have a flow that grabs the email and adds it to a list. If I have the access request sent to myself it works fine. Unfortunately, I'm still looking for an answer.