Why emails sent by PHPMailer fail DKIM check?

Question

Email

I connected DKIM on my hosting to sign sent letters.
The DKIM signature is added on the SMTP server.
I check the validity of the DKIM signature using the www.brandonchecketts.com/emailtest.php
service. When sending via the web mail interface and via the desktop client, the validation passes.
When sending using a PHP script using PHPMailer, validation fails.
At the same time, when sending using a PHP script that uses SwiftMailer, validation passes.

What could be the problem?

Answer 1

pay attention to email headers in different cases

Answer 2

Actually, judging by the headers, instead of DKIM (RFC 4871) you have the outdated DomainKeys (RFC 4870), DKIM uses DKIM-Signature, not DomainKey-Signature. According to RFC 4870, hardly anyone will help you, because in practice it has never been much used. Apparently, somewhere something is not screwed.

Answer 3

Added DKIM instead of Domain Keys and made the following changes to PHPMailer
Line 2282:
change
$headers = explode("\n\r",$headers_line);
to
$headers = explode($this->LE,$headers_line);
Lines 2292 and 2293
change
$from = str_replace('|','=7C',$this->DKIM_QP($from_header)); $to = str_replace('|','=7C',$this->DKIM_QP($to_header));
to
$from = str_replace('|','=7C',($from_header)); $to = str_replace('|','=7C',($to_header));
Line 2297
change
$DKIMb64 = base64_encode(pack("H*", sha1($body))) ;
to
$DKIMb64 = base64_encode(pack("H*", sha1("\r\n" . preg_replace("/\r\n$/", "", $body)))) ;
After that everything worked :)