Message contains NUL characters ...

David R Bosso dbosso at
Thu Apr 28 16:37:03 EDT 2005

--On Thursday, April 28, 2005 4:22 PM -0300 "Marc G. Fournier" 
<scrappy at> wrote:

> Someone mentioned that this was, in fact, not forbid'd in the RFCs ...
> could you point to the relevant RFC where it is?  Considering how
> 'strict' postfix seems to be, having an RFC to back that up might show
> some changes over in that camp, at least ...

>From my reading of RFC 2822 <> section 
4, since the NUL character has been obsoleted, it can no longer be 
generated, so the senders are out of compliance.

Section 4 does say:

> Though some of these
> syntactic forms MUST NOT be generated according to the grammar in
> section 3, they MUST be accepted and parsed by a conformant receiver.


> To repeat an example, though this document requires
>    lines in messages to be no longer than 998 characters, silently
>    discarding the 999th and subsequent characters in a line without
>    warning would still be bad behavior for an implementation.  It is up
>    to the implementation to deal with messages robustly.

and specifically about the NUL:

>    Finally, certain characters that were formerly allowed in messages
>    appear in this section.  The NUL character (ASCII value 0) was once
>    allowed, but is no longer for compatibility reasons.  CR and LF were
>    allowed to appear in messages other than as CRLF; this use is also
>    shown here.

I highly suggest reading sections 3 and 4.


David R Bosso <dbosso at>
Systems & Network Manager, Letters and Science IT
UC Santa Barbara - 1054 North Hall 805 451-7160
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