Re: [exim] SPAM with empty subject field

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Author: Jethro R Binks
Date:  
To: exim-users
Subject: Re: [exim] SPAM with empty subject field
On Fri, 24 Aug 2007, Neil Youngman wrote:

> Mar Matthias Darin wrote
>
> > Here is what I use for this problem:
> >
> > acl_check_data:
> >   deny    condition     = ${if or 
> {{!def:h_Date:}{!def:h_Subject:}{!def:h_To:}}{yes}{no}}
> >           message       = Message does not conform to RFC2822 standard 

>
> RFC 2822 says "The only required header fields are the origination date
> field and the originator address field(s). All other header fields are
> syntactically optional.", i.e. Date: and from: so your error message
> seems to be wrong. RFC 2822 does not require a Subject: or To: field as
> far as far as I can see.


Probably correct; however you may wish to consider the likelihood that a
message with no Date:, Subject: or To: field is legitimate, and tweak its
spam score accordingly if outright rejection is too risky in your
environment (in fact I think the default SpamAssassin ruleset does add
some points for these occurrences, but perhaps not significantly enough
when all three occur at once).

Jethro.

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Jethro R Binks
Computing Officer, IT Services
University Of Strathclyde, Glasgow, UK