On Fri, 2 Apr 2004, Gordon Fecyk wrote:
I asked for a minimum specification for a recieving server looking
to receive the minimum benefit from SPF.
Proposed minimal SPF implementations for mail receivers:
Level 0:
Check a subset of mechanisms: A, PTR, MX, ALL. Be sure that "unknown"
results from an unrecognized mechanism. Do not support macros.
Don't bother with Received-SPF. Note that no recursion is required for the
minimal supported mechanisms.
Level 1:
Check recursive mechanisms and macros: INCLUDE, EXISTS. Add Received-SPF
headers, for inspection by downstream software (e.g. bayesian filters will
learn to use SPF results other than 'fail', including 'neutral' and
'softfail', in recognizing spam). Reject mail giving a 'fail' result with code
551 and the recipient (allows the mail sender to bypass a non-SRS forwarder).
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Very few of our customers are going to have a pure Unix
or pure Windows environment." - Dennis Oldroyd, Microsoft Corporation