On 2023-10-08 at 03:38:00 UTC-0400 (Sun, 8 Oct 2023 18:38:00 +1100)
Erik de Castro Lopo <mle+to...@mega-nerd.com>
is rumored to have said:
Hi,
I am in the process of writing a pre-processor for Spamassassin. It
would
be a pre-processor because I do not read or write Perl.
That would be a solid reason not to attempt a SA 'plugin' but you really
should be considering whether the analysis you are trying to do can be
implemented as local custom rules. SA rules do not require knowledge of
Perl.
The I idea would be to analyse the each email and based on the
analysis add
extra fields to the email header before passing the email to
spamassassin
to do its thing.
My first questions is, will SA detect these new headers and use them
as part
of its analysis?
SA has access to the entire message. SA rules can examine any header,
but SA won't do anything more than treat an arbitrary header as a series
of meaningless tokens for Bayesian classification unless you add rules
that specifically interpret those headers.
Assuming the above is true, I have a couple of options:
1) Always add each new header with a score (which I do not think
would
be very effective).
SA does not look for 'scores' in headers, as it has no way to know what
a score might look like or mean and it can't *generally* trust anything
inside a message as meaning what it claims to mean, e.g. you can't just
send mail with a "X-Spam-Score: -200" and expect SA to treat that as a
score. For SA to interpret the content of a header as justifying a
score, it needs rules that interpret it.
2) Only add a new header if the detected feature is probably spam.
If you are absolutely set on the design concept of putting something in
front of SA, that's probably better. OR, if this is intended mainly to
protect non-spam, only tag that. In any case, you'll need custom SA
rules to understand any sort of meaning in what you add.
Depending on the specific sort of analysis you are doing, it may be
feasible to do it with a construct of SA rules, and that would avoid the
housekeeping issues of how to integrate a 'preprocessor' with your
existing MTA and whatever yopu're using as 'glue' for SA.
(content_filter script, spamass-milter, MIMEDefang, etc.)
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire
