SM wrote:
I sent a comment to one implementer a few years about suggested
switching to 450 as the code can be used to signify that it is a
temporarily blocked for policy reasons. I know another implementation
that uses "450". Refer to Section 4.2.2 of RFC 5321 for further
information.
I think you're right to use 450 based on the enhanced 5321 text.
But from 2003 and before RFC5321, Harris only had RFC2821 which didn't
include the new "temporarily blocked" text.
The main thing is to help reduce Greylisting hurting rapid delivery
using smarter retries than the recommended 30 mins and if there are
Harris based systems out there, they might be looking for 451 as a
trigger.
--
Sincerely
Hector Santos
http://www.santronics.com