There are a number of mailing lists on the internet and a fair number of them are genealogy related.
The two best places to find other genealogy related lists is Vicki Lindsay's web page:
http://www.eskimo.com/~chance/
and John Fuller's ``Genealogy Resources on Internet'':
http://users.aol.com/johnf14246/gen_mail.html
The original genealogy mailing list, ROOTS-L, is also run on rootsweb.com. Take a look at the rootsweb web page for more information:
http://www.rootsweb.com/