As of this writing (May 2008) the Russian spelling of the word "e-mail" has still not stabilized in the literary language. Style guide "gramota.ru" advises Russians to write it in English letters as "e-mail." That of course is not at all satisfying to those of use who are desperate to use our hard-won Russian skills to the nth degree. The same site advises the spelling имейл if you are determined to use Cyrillic.
Colloquially Russians also sometimes refer to e-mail as мыло, the same word they use for "soap." You'll hear that often from programmers, techies, and Russians who like to play with English. Among people over thirty the word электронка is often used.
Rev. 15 May 2008