I have one user in the office that sends a .pdf attachment to 2 different external recipients. Each of these recipients will receive the e-mail with the attachment, but instead of a .pdf, it will be a .png. All other users in this organization can send to these 2 same users and the attachments are received correctly. Any ideas? In the sent items, it shows up as a .pdf attachment. She can send the exact same attachment to any other external recipient, and it arrives correctly as a .pdf.