>   I think that I would be very critical of a paper that came to me for
> review that had too many citations to email and not enough indication of a
> deeper analysis.
It really depends on the subject of the paper. Doesn't it?  A paper surveying
current opinions on a subject could legitimately use email and newsgroups
as a major source.  A paper analysing the development of thought in a subject
would be doubtful if email was the major source. But as a former tutor said
to me "if you use it cite it" (I can't remember his/her name, pers. com., 1982)
of course if it was a chat in the pub with the Professor of Archaeology you
dress it up as a 'personal communication'!
 
--
Trevor Reynolds