One of my users sent an email that mistakenly contained an attached pdf file. He says that he didn’t attach the pdf file and it wasn’t there before he sent it. So, he is a bit freaked out about how the file got attached.

The only methods I know of inserting an attachment into an email is to use the 'Insert file' icon that looks like a small paperclip, use Copy/Paste or click a file and drag and drop into the message.

The PDF file in question was saved to the clipboard, so I think that it is possible that he mistakenly clicked ctrl-v to paste it in. He insists he didn’t and the attachment didn’t show up until after he sent?

I’m not aware of any malware that would paste clipboard contents into Outlook message?

Any ideas?