[Dovecot] configuration user= or auth_user=

[Phil Howard]

The sample config file has:

  # User to use for the process. This user needs access to only user and
  # password databases, nothing else. Only shadow and pam authentication
  # requires roots, so use something else if possible. Note that passwd
  # authentication with BSDs internally accesses shadow files, which also
  # requires roots. Note that this user is NOT used to access mails.
  # That user is specified by userdb above.
  user = root

  # Directory where to chroot the process. Most authentication backends
don't
  # work if this is set, and there's no point chrooting if auth_user is
root.
  # Note that valid_chroot_dirs isn't needed to use this setting.
  #chroot =

So is the variable for the authentication process user supposed to be "user"
or "auth_user"?  It would make more sense to be "auth_user".  Is it just
"user" for legacy reasons, and the reference to "auth_user" is in error?  Or
can either name be used?

Also, those of you who change this, do you change it to something existing
like "dovecot" or "vmail" or "nobody" or do you make a whole new user for
it?