In this case, I think the correct response would be 501, since it is a
syntax error in the argument to MAIL.
On Tue, 18 Jul 2000 Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu wrote:
(Am cc'ing the IETF-SMTP list, hopefully it's alive and somebody there
will have guidance on this... For the IETF-SMTP list, the discussion is
what to properly do if handed this during an SMTP transaction:
MAIL FROM:<user(_at_)domain(_dot_)name@other.domain>
Sendmail currently issues a '250 OK'.
On Tue, 18 Jul 2000 10:46:13 PDT, Kyle Jones
<kyle_jones(_at_)wonderworks(_dot_)com> said:
The attitude I took when I ran a relaying server was that stuff
like a(_at_)b@c was better off bounced immediately.
I can deal with that attitude.
However, RFC821 also lists the following codes on page 56:
550 Requested action not taken: mailbox unavailable
[E.g., mailbox not found, no access]
551 User not local; please try <forward-path>
552 Requested mail action aborted: exceeded storage allocation
553 Requested action not taken: mailbox name not allowed
[E.g., mailbox syntax incorrect]
554 Transaction failed
But then continues to say:
MAIL
S: 250
F: 552, 451, 452
E: 500, 501, 421
RCPT
S: 250, 251
F: 550, 551, 552, 553, 450, 451, 452
E: 500, 501, 503, 421
(I.e. you can toss a 553 on the RCPT TO, but not on a MAIL FROM).
RFC1123 then muddies things up more:
5.2.10 SMTP Replies: RFC-821 Section 4.2
A receiver-SMTP SHOULD send only the reply codes listed in
section 4.2.2 of RFC-821 or in this document. A receiver-SMTP
SHOULD use the text shown in examples in RFC-821 whenever
appropriate.
A sender-SMTP MUST determine its actions only by the reply
code, not by the text (except for 251 and 551 replies); any
text, including no text at all, must be acceptable. The space
(blank) following the reply code is considered part of the
text. Whenever possible, a sender-SMTP SHOULD test only the
first digit of the reply code, as specified in Appendix E of
RFC-821.
DISCUSSION:
Interoperability problems have arisen with SMTP systems
using reply codes that are not listed explicitly in RFC-
821 Section 4.3 but are legal according to the theory of
reply codes explained in Appendix E.
So, is it legal/permissible/suggested to 553 on a MAIL FROM that can be
determined to be syntactically invalid?
--
Valdis Kletnieks
Operating Systems Analyst
Virginia Tech
---
Gregory Woodhouse
gjw(_at_)wnetc(_dot_)com / http://www.wnetc.com/home.html
"An atheist staring from his attic window is often nearer to God than the
believer caught up in his own false image of God."
--Martin Buber