The 'mail' system account

[David Garamond <lists@zara.6.isreserved.com>]

Dear all,

In what package is the 'mail' system account defined and how do I find 
this out? I've seen 'mail' even in the most minimalist installations 
(without exim or mailx), but I'm not sure that if I put stuffs in 
/var/mail it won't get deleted when some package removal include the 
removal of the 'mail' system account.

Regards,
dave