Message contains NUL characters ...

John Fawcett johnml at
Mon May 9 14:51:09 EDT 2005

Greg A. Woods wrote:
> [ On Sunday, May 8, 2005 at 21:35:58 (+0200), John Fawcett wrote: ]

>>I am very happy with postfix!
> Apparently Postfix suffers a design flaw in that its internal dictionary
> lookup API uses NUL-terminated strings so it is not possible for it to
> easily use any regex pattern in header_checks or body_checks to match
> NULs -- the regex engine simply won't ever see the NUL in a header or
> body line passed to it to be matched, and instead it'll just see a
> shorter NUL.  (Note this is a bit more serious than one might suspect on
> first glance since it probably means an embedded NUL can hide further
> content on the line from header_checks and body_checks!)
as I understand it's the nuls in the header/body checks which
are not supported, not the presence of a nul in the message which
prevents header/body checks being applied.
> However once upon a time not so long ago (2005/04/02), on the Postfix
> users mailing list, Wietse Venema said:
>     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.
> So apparently the proper fix should be quite easy to implement, and done
> right a patch is likely to be accepted back by Wietse as well.
I am actually looking at this too, but that will benefit only postfix
users not all users of cyrus.

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