I recently received a report that attachments sent to Gmail from some servers were being corrupted. At first, I assumed that the reporter was mistaken, or that perhaps the problem was with the sender's mail client or server. One of my colleagues had already conducted some tests of his own and found that PDFs and TIFFs he tested with were indeed being corrupted. I had to investigate. Some quick tests proved that the reporter and my colleague were correct. Below is detailed information about the tests I conducted and my findings.