The Collaborative International Dictionary of English v.0.48:

E-mail \E-mail\, email \email\, e-mail \e-mail\([=e]"m[^a]l`),
   n.
   electronic mail; a digitally encoded message sent from one
   computer to another through an electronic communications
   medium, especially by means of a computer network.

   Syn: electronic mail.
        [PJC] email
        E-mail

The Collaborative International Dictionary of English v.0.48:

E-mail \E-mail\, email \email\, e-mail \e-mail\v. t. [imp. & p.
   p. E-mailed; p. pr. & vb. n. E-mailing.]
   to send (an e-mail message) to someone; as, I emailed the
   article to the editor; she emailed me her report.

   Syn: mail electronically.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

email
    n 1: (computer science) a system of world-wide electronic
         communication in which a computer user can compose a
         message at one terminal that can be regenerated at the
         recipient's terminal when the recipient logs in; "you
         cannot send packages by electronic mail" [syn: electronic
         mail, e-mail, email] [ant: snail mail]
    v 1: communicate electronically on the computer; "she e-mailed
         me the good news" [syn: e-mail, email, netmail]

The Jargon File (version 4.4.7, 29 Dec 2003):

email
 /ee'mayl/

    (also written ?e-mail? and ?E-mail?)

    1. n. Electronic mail automatically passed through computer networks and/or
    via modems over common-carrier lines. Contrast snail-mail, paper-net, 
    voice-net. See network address.

    2. vt. To send electronic mail.

    Oddly enough, the word emailed is actually listed in the OED; it means ?
    embossed (with a raised pattern) or perh. arranged in a net or open work?.
    A use from 1480 is given. The word is probably derived from French ?maill?
    (enameled) and related to Old French emmaille?re (network). A French
    correspondent tells us that in modern French, ?email? is a hard enamel
    obtained by heating special paints in a furnace; an ?emailleur? (no final
    e) is a craftsman who makes email (he generally paints some objects (like,
    say, jewelry) and cooks them in a furnace).

    There are numerous spelling variants of this word. In Internet traffic up
    to 1995, ?email? predominates, ?e-mail? runs a not-too-distant second, and
    ?E-mail? and ?Email? are a distant third and fourth.