postfix config - root not receiving mail, but others are

[Dale Scott]

Hi, I'm building a self-contained proof-of-concept, and configuring Postfix
in place of Sendmail. I'm using Mutt on the command line view mail sent by
the local web apps to the users (step #2 will be providing IMAP/POP3 access
via Dovecot). Just using Mutt, it seems root can email local users, and
local users can email each other, but local users can't email root - or at
least mail to root isn't received.

Any ideas? Where might I have gone wrong? Fwiw, I have *not* set an alias
for root in /etc/mail/aliases, on the basis that all mail to root needs to
end up in root's Maildir

Thanks,
Dale