DKIM fail if WHM adds Message-ID, should be Message-Id

[@lbutlr]

> On 12 Oct 2020, at 03:06, Tom Hendrikx <tom at whyscream.net> wrote:
> 
> On 12-10-2020 10:16, Robert Martin wrote:
>> I created a client library to send emails for a webapp.
>> 
>>  
>> After connecting to the SMTP server with credential setup in CPANEL, and then do NOT add Message-Id header, the DKIM signature 'h' record created by dovecot/WHM is wrong, and a Message-ID (with a capital D) header is added, invalidating the generated DKIM signature value.
>> 
>>  
>> This causes outlook, yahoo, gmail and other email recipients to add 'dkim:fail' to the message, and thus relegate it to junk or spam.
>> 
>>  
>> The work around is to add to the message a Message-Id with a  little ‘d’ header.  Then the SMTP server processes the email with the correct generated DKIM, correct DKIM ‘h’ record and does not add a Message-ID header.
>> 
>>  
>> My SMTP hosting providers that run the WHM/dovecot/CPANEL software are refusing to raise this as a bug and have requested that I do it.
>> 
> Hi Robert,
> 
> Dovecot does not add DKIM headers, Dovecot doesn't even send email. Aside from that:
> 
> - The RFC states that "Message-ID" is the actual spelling: https://tools.ietf.org/html/rfc5322#section-3.6.4

The RFC (5322) states that the headers are not case sensitive:

"This specification uses the Augmented Backus-Naur Form (ABNF) notation for the formal definitions of the syntax of messages.  "

RFC 5234
NOTE:

      ABNF strings are case insensitive and the character set for these
      strings is US-ASCII.

So message-id:, MessAGE-iD:, and Message-Id: are all valid.

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