I have a user that after sending a message outside our domain that nessage attachment extension .pdf is stripped and then the icon of the PDF attachment changes to a bitlocker "unlocked" icon. The conditions are very specific:
- Only to external emails
- Only PDFs
- Only when the user sends on behalf of
The recipient can save the attachment locally and add the .pdf extension back to the message and it will open normally. I am at a loss to explain. As far as I know, Bitlocker and Outlook do not have any known interaction. Im wondering if the user she is sending on behalf of may unknowingly implemented some form of security on his mailbox via Outlook settings.