Attachments are dangerous. For a long time, that's how viruses propagated. That's not as much the case anymore, but Microsoft decided in more recent versions of Windows to prevent attachments unless he were to allow them. In Gary's situation, since he's using Hotmail on the web and only having issues with one or two friends, Leo suspects it's something on their end. Gary should find out how they're attaching these photos, because it could be just attaching improperly.