I had one of those moments recently. The moment of fighting the authority of spell check. It is sad. So sad because, I honestly thought–not thought—knew—my word was legit. The word was prepend. The word means is the antonym of append or the same meaning as prefix.
If you have a computer programming background, you may very well agree with me. My research quickly found that it is not an “official” word. But, I also found that it is used often and frequently in programming. Hence although not a word, it is being used which means that in time it will be “official.”
On another note, please do not use the hyphen in email. My back twitches, as if I heard the nails on a chalkboard, whenever I see e-mail.