[This is a fast-access FAQ excerpt.]
In September 1995, Jeff Adams (jeffa@kurz-ai.com) did a search on
"a corpus of about 40 million words of Usenet news articles", and
counted the following forms:
email 19371
e-mail 15359
E-mail 7572
Email 5906
E-MAIL 3659
E-Mail 2986
EMAIL 1269
EMail 521
eMail 303
e-Mail 42
eMAIL 5
and several other forms each rare enough to be probably "just dumb
typos".
Total without hyphen: 27378
Total with hyphen: 29622
Bob Cunningham searched articles posted to alt.usage.english
between mid-May and mid-September 1995, found 604 instances of
"e-mail" and 235 of "email".
A 1995 poll of subscribers to the Copyediting-L mailing list
produced 60 votes for "e-mail" and 24 votes for "email".
In favour of "e-mail", it has been argued that there are
analogous nonce compounds in "e-" (e.g, "e-vote", "e-boyfriend");
that the hyphen is a clue that the word is stressed on the first
syllable; and that email is French for "enamel". In favour of
"email", it has been argued that this is the spelling used in the
Jargon File, and that there has been a general trend away from
hyphenating words once they become established. Many dictionaries
favour "E-mail", which can be justified by analogy with such forms
as "A-bomb", "C-section", and "G-string".
[See more statistics for numbers of people using the
spellings 'e-mail' and 'email'.]