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

[Adi Pircalabu]

On 12-10-2020 19:16, 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.

Hardly a bug imo. Best to add the Message-Id header from your library 
and this will become a non-issue. There are certain filters who don't 
quite like emails without message-id header, or incorrectly formatting 
ones because this is an usual fingerprint of a broken client / spam bot, 
this is why your provider is adding that header.

-- 
Adi Pircalabu