From Washington Post copy chief Bill Walsh’s excellent blog, The Slot:
The problem with “e-mail” is that it’s not a simple compound noun. It’s an initial-letter-based abbreviation, and no initial-letter-based abbreviation in the history of the English language has ever morphed into a solid word. The “e” isn’t simply a syllable — it’s the letter e, for Chrissakes, like the X in “X-ray.” Nobody lives in an “aframe,” nobody drives a “zcar,” and you will find no example parallel to the illiteracism “email.” “Email” (the French word for “enamel,” by the way) divorces the e, ee, eee! so that the first syllable begs to be a schwa sound. Uhmail. Uh.
Prairie dog is with Walsh on this one. Dissenting writers are ordered to surrender immediately. No more “email” in this paper. No! Bad!
For further reading I recommend Walsh’s book Lapsing Into A Comma. It’s very good. And really funny.