patch against NUL chars

Simon Brady simon.brady at
Thu May 8 11:09:37 EDT 2003

On Thu, 8 May 2003, Nikola Milutinovic wrote:

> Is there a legitimate reason for NUL chars in an e-mail message?

Not as far as I know.

> If not, how are they getting there?

Goblin mischief? After upgrading our site of ~15-18K users to cyrus 2.1 we 
started seeing 1-2 messages with NULs a week, but were never able to 
conclusively determine the cause. Broken clients is the most obvious 
answer, but why so intermittently?

> And why should you give a damn?

It gets a bit messy when sendmail tries to report the "message contains 
NULs" DSN to postmaster and includes the original message... Luckily the 
message is dropped with a "losing queue" comment rather than looping.

The quick solution we adopted, courtesy of someone on this list, was to
upgrade to sendmail 8.12 and use the F=1 delivery agent flag to strip NULs 
before lmptd even saw the messages (see p748 of the Bat Book, 3rd ed). 
This solved the problem without having to touch cyrus.

Simon Brady                             mailto:simon.brady at
ITS Technical Services
University of Otago, Dunedin, New Zealand

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