From: Wietse Venema (wietseporcupine.org)
Date: Sat Apr 02 2005 - 08:19:23 CST

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Per olof Ljungmark:
> Hi list,
>
> I have been reading through several posts regarding the NUL character in
> mail body. As we are running a postfix/cyrus combo and occasionally
> see this with non-spam senders I would like to hear how others on the
> list deal with the problem:
>
> a) Have Postfix alter the body
> b) Change the Cyrus source
> c) Reject
> d) additional options?
>
> I would like to do c) with Postfix (not Cyrus) but with additional info
> if the bounce is non-spam sender, along the lines of
> ->spamtrap->smtpd->554 ...
> ->user->smtpd->BOUNCE with link to additional info
>
> Can this be accomplished in a fairly simple fashion with Postfix 2.2?

The problem is that some high-quality proprietary mail software
can't handle mail with nulls.

Postfix has an option to flag and reject 8-bit content in message
bodies that are announced as 7bit; this could be duplicated with
minor change to flag and reject nulls in body content. It's only
a dozen lines of code, and a dozen or lines of documentation. I
won't do it as I am working on other stuff.

It is, however, not practical to make the RESPONSE to a MIME error
dependent on the origin of a message. You'd have to set up different
levels of strictness for trusted and untrusted senders.

        Wietse

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