I started to get this message when I opened one attachment in the received email in the Mail on my Macbook Pro. I opted for Skip, but it kept popping-in, so I chose Download (there were only two options), it downloaded the file after a while in the unusual format, so I thought it would be the end of the matter. I restarted my laptop, but the message still pops in. I deleted the attachment I saved, but it keeps doing. Please help me to get rid of it altogether. Thank you. Lucy Heron