[Esa-l] Doing mail filtering in Sendmail itself

[Mark A. Hershberger]

Brett Glass <brett at lariat.org> writes:

> It's very unusual to have no local delivery at all. In fact, 
> IIRC, it violates an RFC or two.... Every host that does SMTP is
> supposed to have mailboxes for the admin and postmaster.

     RFC 822 (6.3):

     This standard specifies a single, reserved mailbox address
     (local-part) which is to be valid at each site.  Mail sent
     to that address is to be routed to a person responsible for
     the site's mail system or to a person with responsibility
     for general site operation.  The name of the reserved
     local-part address is "Postmaster" so that
     "Postmaster at domain" is required to be valid.

So mail is to be "routed" to the person responsible, but not
necessarily locally delivered.

     RFC 1123 (5.2.7):

     A host that supports a receiver-SMTP MUST support the
     reserved mailbox "Postmaster".

Without context, one might read this and think that it is talking
about a local file.  At another point in the RFC, though, it
explicitly mentions "locally-registered" mailboxes.  That
distinction is missing from the above quote.  Throughout the RFC,
in fact, the term "mailbox" covers a wide variety of mail
destinations.

Perhaps a more relevant RFC to my site is RFC 1648 ("Postmaster
Convention for X.400 Operations") since the ultimate destination
is delivered according to a lookup against an X.500 directory.

This RFC talks about mapping RFC822 addresses to X.400 mail
domains.  No mention is made of mandatory local delivery.

 From my reading, it looks like pure-relay SMTP hosts are
completely RFC-compliant.

Mark.

-- 
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