Personally, I've gotten better at writing the response and then throwing it away. As noted earlier, this type of 'therapy' can be great for either calming one down or helping one realize that there is no gain to sending the email at all.

Our former CIO came down fairly and squarely on IT for this very issue. For a time after that, I was my boss' official proofreader for any emails to the CIO that had any critical content. More than one I talked him down to something more pleasant and it all worked out in the end.

So make like Santa Claus. Make the email, check it twice. If necessary, get an elf to look over it for you. The embarrassment you save may be your own.