Hi !!
That's a good point, esspecially considering all the cable modems out there
that have valid A record lookups. The SPF method, though more complicated,
would give the ability to FAIL those situations.
there is always a situation where we cannot do some checks, what i
would suggest is:
- if a sender is avaiblable test it with spf
- if spf check gives fail, reject the message
- if spf check gives pass, accept the message
- in any other circumastance, if the helo is not an ip literal
check it
- if it passes the check, accept the message
- if it fails the check, reject the message
then it only lefts the case of a null envelope sender using an
ipo literal in the helo, which will require something like mtamark
to be checked
BTW, in the past i also have the temptation to use spf to check
the header from: for nuvll envelope sender messages.
--
Best regards ...
It's a fine line between fishing & standing still
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