Issue DKIM email control not valid

[Erwan]

Server operating system version

AlmaLinux 9.4

Plesk version and microupdate number

18.0.63

Hi all,

I configured DKIM for a domain via Plesk ("use the DKIM anti-spam system to sign outgoing emails").
The entries are in the DNS.
> default._domainkey.mydomaineB.com ==> v=DKIM1; p=MIGfM.....
> _domainkey.mydomaineB.com ==> o=-
> _dmarc.mydomaineB.com ==> v=DMARC1;p=none;rua=mailto:....

When I test a shipment for example. with a PHP function in domain hosting,

$headers = "From: [email protected]\r\n" .
"Reply-To: [email protected]\r\n" .
"Return-Path: [email protected]\r\n" .
"X-Mailer: PHP/" . phpversion();
$parameters = '-f mydomaineB.com';
mail("[email protected]", "This is a test", "This is a test.", $headers, $parameters);

DKIM signature is not valid.
With Gmail:

ARC-Authentication-Results: i=1; mx.google.com;
dkim=fail [email protected] header.s=default header.b=Pnwz1tTx;
...
With another:
DKIM not valid.
..
v=1;
a=rsa-sha256;
c=relaxed/relaxed;
d=wedge.area-team.fr;
s=default;
...
Your public key is:
"v=DKIM1;
p=MIGfM...
...
Key length: 1024bits
Your DKIM signature is invalid

The domain is managed with 3 other domains with a Plesk Admin license.
I don't know if this has any consequence but a few months ago these domains were under a single subscription with a main domain on a server with a Plesk Pro license.
We used Plesk Migrator.

How to fix this? Thank you.

Erwan

 

[Martin Dias]

Please check if these topics on this matter that might help you, if not provide details on why not so we can check further:

Resolved - PHP Mail is not signed with DKIM

Hello, When I send email from the Round Cube web client, the email is signed signed with DKIM. However when a website sends email via PHP mail it is not signed with DKIM. OS: ‪Ubuntu 16.04.1 LTS‬ Product: Plesk Onyx 17.0.17 Update #3 How can i ensure PHP mail also gets signed with DKIM...

talk.plesk.com

Resolved - Location > DKIM verification > Plesk milter (Postfix) / Postfix within Plesk

Slightly detailed explanation, but at least there's only one question at the end :) and we're sure that somebody on here, will know the answer. We're almost at the stage of successfully applying DKIM to all PHPMailer sent e-mails on some of our domains that now require this option. We're testing...

talk.plesk.com

Also feel free to vote for it here:

Add DKIM-key in php mail() function

When DKIM is activated, the key isn't added when you use the PHP mail() function, for example if you have a contact form on the website. Please add because this generates false SPAM-detection problems. Google for example thinks it's strange that sometimes the DKIM key is added and sometimes not...

plesk.uservoice.com

 

[Erwan]

Thank you.

So I carried out tests with PhpMailer (not mail()) to be able to force authentication.
It doesn't change anything.
Sending via RoundCube is not good either.

Always:
Authentication-Results: mx.google.com;
dkim=fail [email protected] header.s=default header.b=t0GdT...

I had the idea of putting an email from the old main domain name and then surprise: DKIM is ok.

Authentication-Results: mx.google.com;
dkim=pass [email protected] header.s=default header.b=PaEd...

The domains are in the same web space.
This seems to influence which DKIM to use.

Web space : mydomaineA.com
System user : myftpsystem
IP : xx.xx.xx.xx
Companion domains :
- mydomaineA.com
- mydomaineB.com (with the email [email protected])
- mydomaineC.com
In summary, the website is : www.mydomaineB.com.
If i send email with: [email protected] (PhpMailer or Round Cube), DKIM fail.
If i send email with: contact@mydomaineA.com (email address that does not exist), DKIM pass
An idea of what to do...