is i send a test mail from joomle and from a order, - there is differenses

Hi,

HikaShop has email settings under the main tab of the HikaShop configuration so that you can setup a different "from" email address, and a different "bounce" email address than what is used by Joomla.
This can also be overridden via the System>Emails menu for each email with the Business edition.
So it's possible that the difference you get is linked to you using a different email address in these.
Also, the emails HikaShop sends contain HTML with images, layout, etc, while the emails Joomla sends are simple text emails.
Now DMARC normally relies on SPF and DKIM for authentification of the email server. And SPF is something you setup with your domain name and DKIM something you setup with your domain name and email server.
And even DMARC is something you normally setup on the email server.
So normally, there is nothing you can do in HikaShop. It's probably a config issue on the server side of things.

Hi,

I don't know as you didn't provide precise information about neither emails on your end.
DMARC/SPF/DKIM headers are added to emails by the email server.
You can see this if you look at the headers of the emails in your email client.
For example, on GMail, when you have an email opened, you have a button "more" (3 dots vertically aligned) and if you click on it, you can choose "show original". This will display all the headers of the email:
monosnap.com/file/MYzMrPw8KM0sdviznPNz24phcTQCpE
And thus, you can compare the headers of both emails to see what is different, and it might help you or us find out what's wrong.

Hello,

DKIM, DMARC, OpenARC, SpamAssassin are emails modules which need to be configured with your email server (such as Postfix, QMail, Sendmail, Exim, etc).
If you're using an external SMTP server, that server should provide you the DKIM (and other) tools ; thus when you want to send an email, you're email client should not have to know your DKIM settings (and your keys) to sign the content.
The email server should check that you have the right to send an email and then, approved it.

Joomla does not have extended email settings to generate the DKIM signature, okay.
Now acymailing (and I suppose other components specialized in emails/newsletters) do have that kind of feature since they need to send a huge number of emails and that's also their core feature.
When you configure the DKIM in acymailing, you have to create a new DKIM entry in your DNS server ; thus it won't use the same domain than your email server (not sharing private key, better for security).

Should HikaShop and other Joomla components implement DKIM features ?
Clearly no. It would mean that nobody would use the Joomla core in order to send email, everybody will have its own implement, everybody will ask you to create a new DKIM domain for their emails, everybody should maintain their PHP email lib, etc.

Would it be great if Joomla could have DKIM settings for the emails ?
It could be interesting for many users, of course.

I don't know how your website is hosted and what kind of email server you're using.
But I do recommend that DKIM is made by the application which handle emails.
When your postfix is right configured, it will verify and generate the DKIM in the received/sent email ; it will do the job it is meant to do.