In the very early days of lolcats, I nearly got fired because an image macro I referenced in an email got replaced, several months later, with.... let's just sa

In the very early days of lolcats, I nearly got fired because an image macro I referenced in an email got replaced, several months later, with.... let's just say it was the sort of image that rivals goatse for disgusting. Fortunately, my company's IT department had enough of a clue that when I explained what had happened, they agreed it was possible; it was a tense week, though, while they investigated. I'm not saying the sort of reaction in parent isn't always appropriate, but just be aware that people's lives can be ruined to save a few dollars. I think the OP's solution is ideal: it alerts people to the problem in a very professional way, and provides solutions for the most common cases.