Alicia Rosov: This one varies. Writing to authors and clients, I use option A. For less formal contacts, friends and colleagues, I use option C.

Tom Kreitzberg: I won't miss the day when C is the unquestioned norm.

G. Miki Hayden: A. email is fine, also.

L. L. Thrasher: I like the hyphen but I think fighting it is a lost cause.

Yocheved Golani: B is easier on the eyes, is clearly intentional and thus not a typo.

Elayne Cree : I use both e-mail and email, depending on the environment. The latter is what I use in email correspondence, primarily because it's easier to type than e-mail (don't have to go to top row for the hyphen).

Christi: Although I'd love it if C were the norm!

Charlotte Fox Luttrell: No need for capital letters in middle of sentence. Email is not a word.

Mark H. Bloom: This is a company-wide style, but it is also the one I prefer.

Carrie Garbas: Always hyphenate. And why even think of capitalizing?