I am always disgusted and angry at people who use non-standard, closed, and proprietary formats for the attachments they send me. I have always been quietly deleting their mails along with the attachments. I discovered recently that I am not the only one to do this, and I am not being impolite or harsh or unreasonable.
Here is evidence in support of my campaign to rid the world of such pests::
So, stay away from non-standard, closed, and proprietary formats, if you want me to read your mails fully.