Re: Question about message_drop_headers and DKIM

[Wietse Venema]

J Doe:
> BUT . . . If message_drop_headers is extracting some header
> information *BEFORE* running the OpenDKIM Milter, how is it that
> DKIM is not breaking ?

That is because the DKIM signature covers only the headers that 
are mentioned in the signature.

Wietse

Question about message_drop_headers and DKIM

[J Doe]

Hi,

I have a question regarding the message_drop_headers main.cf configuration 
parameter.

The man page states that it:

“[specifies] names of message headers that the cleanup(8) daemon will
 remove after applying header_checks(5) and *BEFORE* invoking Milter
 applications...”

Checking man 8 cleanup I note this relates to:

“...inbound mail...inserting into incoming mail queue...”

On the smtpd(8) server process, I have OpenDKIM configured to run as a Miller.  
It currently notifies me in the log if DKIM signatures on incoming mail were 
found and if it was able to validate them.

BUT . . . If message_drop_headers is extracting some header information 
*BEFORE* running the OpenDKIM Milter, how is it that DKIM is not breaking ?  
Isn’t that discarding header information that would be used in computing the 
DKIM signature ?

Thanks,

- J