DKIM and MailScanner used in a mail forwarder

[Julian Field]

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On 9/3/09 09:06, Julian Field wrote:
> * PGP Signed: 03/09/09 at 09:06:48
>
>
>
> On 9/3/09 01:30, Alex Neuman wrote:
>> I believe it's been tried before with sendmail but, as Brent 
>> mentions, you have to have an instance of sendmail that does the 
>> actual signing after MailScanner's done with the message.
> Yes, I have separate incoming and outgoing mail systems. And yes, I 
> guess I mean "redirect" and not "forward". Many ISP's offer mail 
> forwarding ("redirecting") for addresses at a customer's domain. So 
> how does anyone else deal with this problem?
>>
>> On Sun, Mar 8, 2009 at 5:45 PM, Brent Addis <brent.addis at spit.gen.nz 
>> <mailto:brent.addis at spit.gen.nz>> wrote:
>>
>>     I use it, it's fine. Exim only signs when it actually sends the
>>     message, so it includes the mailscanner headers.
>>
>>     No idea about postfix/sendmail/whatever else
>>
>>     Make sure you have separate sending and receiving systems (Sending
>>     signs, receiving checks)
>>
>>
>>
>>
>>     On Sun, 2009-03-08 at 11:37 +0000, Julian Field wrote:
>>>     How badly does DKIM interact with MailScanner when MailScanner 
>>> is used
>>>     in a mail forwarding system?
>>>     What could I do to improve the situation?
>>>
>>>     Jules
It appears that DKIM doesn't take the order of most of the headers into 
account after all (I read the spec a bit more thoroughly). It only 
worries about the headers which are named in the "DKIM-Signature" 
header. So there's no need to move the new headers to the top of the 
message after all. Though I will probably leave the option in place, as 
people have asked for it in the past.

Unfortunately the list of headers that appear in the list is a bit long, 
and includes some that MailScanner may inadvertently tweak, such as 
Content-Type, Content-Transfer-Encoding and Message-ID.

Jules

- -- 
Julian Field MEng CITP CEng
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PGP footprint: EE81 D763 3DB0 0BFD E1DC 7222 11F6 5947 1415 B654


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