> One of my users is seeing repeated fails to send to hosted mail for nsf.gov > from qwest.net:
> first MX: > >>>> ... while talking to stn-mtpe-01-03-p.inet.qwest.net.: > >>>>>>> DATA > >>>> <<< 451 4.3.2 Please try again later > >>>> <[email protected]>... Deferred: 451 4.3.2 Please try again later > >>>> <<< 503 5.0.0 Need RCPT (recipient) This is actually both a client and server quality issue. When pipelining is supported (and this server does support it) the client may send a DATA command before confirming that any RCPT TO command is accepted. And when the RCPT TO is reject, as it was here, the server is supposed to reject the DATA command. RFC 2920, section 3.2: (3) SHOULD issue a positive response to the DATA command if and only if one or more valid RCPT TO addresses have been previously received. The RFC doesn't specify whether the negative response should be 4yz or a 5yz (it should - my bad), but since the underlying error is "no valid recipients" use of a 5yz is not unreaonable. It follows that (a) A high quality client should be able to deal with the use of 5yz in this case, and respond according to the RCPT TO error, and (b) A high quality server will keep track of whether or not a temporary failure was issued to any RCPT TO, and if it was issue a 4yz no valid recipients error. > second MX: > >>>> ... while talking to cec-mtpe-01-03-p.inet.qwest.net.: > >>>>>>> DATA > >>>> <<< 554 5.7.1 Access denied > >>>> 554 5.0.0 Service unavailable > >>>> <<< 503 5.0.0 Need RCPT (recipient) Of course you don't know the reason for the rejection, but this does look bogus. Ned _______________________________________________ mailop mailing list [email protected] https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
