On 5-10-17 09:43, Michael Fox wrote:
I'm trying to understand what triggers the setting of
$SuspiciousCharsInHeaders and $SuspiciousCharsInBody?  All I can find are
circular definitions that vaguely mention possible exploits.  But no
specifics are given.  Before I use either of these, I'd like to understand
better what constitutes "suspicious" in both cases.

In both header and body, a CR that is *NOT* followed by a LF is considered 
"suspicious".

In the body, a NUL character is also considered suspicious.

Do you bounce every message that for which $SuspiciousCharsInHeaders is
true?

Yes, we have been bouncing those for over a decade. No complaints so far. But it doesn't 
match a lot of messages (a handful each day out of a few million). And it occasionally 
also matches some seemingly "legitimate" messages that simply aren't formatted 
properly.

How about every message for which $SuspiciousCharsInBody is true?

Tried that briefly and turned it off again. Can't remember why, probably 
because of false positives (that was in 2004). We currently ignore suspicious 
characters in body, don't even log it.

--
Jan-Pieter Cornet <[email protected]>
"Any sufficiently advanced incompetence is indistinguishable from malice."
    - Grey's Law

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