Every site should accept/respond to "postmaster" -- T/F?
" Any system that includes an SMTP server supporting mail relaying or
delivery MUST support the reserved mailbox "postmaster" as a case-
insensitive local name. This postmaster address is not strictly
necessary if the server always returns 554 on connection opening
(as described in section 3.1). The requirement to accept mail for
postmaster implies that RCPT commands which specify a mailbox for
postmaster at any of the domains for which the SMTP server provides mail
service, as well as the special case of "RCPT TO:<Postmaster>" (with no
domain specification), MUST be supported.'
Or is it "Every site running mail"....
Or every box running mail?
I infer all the above from RFC2821 above.
IOW: Which of the following are required vice recommended vice
best practives, etc.
Surely required. RFC2821 above.
Required IFF mail.example.com has an SMTP daemon:
'A host that supports a receiver-SMTP MUST support the reserved
Not required, but encouraged, RFC 2142:
" For well known names that are not related to specific protocols, only
the organization's top level domain name are required to be valid. For
example, if an Internet service provider's domain name is COMPANY.COM,
then the <ABUSE@COMPANY.COM> address must be valid and supported, even
though the customers whose activity generates complaints use hosts with
more specific domain names like SHELL1.COMPANY.COM. Note, however, that
it is valid and encouraged to support mailbox names for sub-domains, as
Postmaster is related to a protocol (SMTP) so this does not exactly
apply. Still, my logs show sending mail to sub-domains is a very
common practice so I always MX all subdomains.
I find this confirmed in RFC1123:
"Be liberal in what you accept, and
conservative in what you send"
and most important to me: where to I go to justify the
decisions on same?
RFC822, RFC1123, RFC2142, RFC2821.