DKIM fails when I use version >= 6

[heminei]

Hi,
When I update PHPMailer from version 5.2.27 to 6.0.7 DKIM stop working. When reverting to v5.2.27 DKIM works properly.

Sample code:

$mail = new \PHPMailer();
$mail->isHTML();
$mail->CharSet = "UTF-8";
$mail->DKIM_domain = 'example.net';
$mail->DKIM_private = '.htkeyprivate';
$mail->DKIM_selector = 'phpmailer';
$mail->DKIM_identity = "test@example.com";
$mail->DKIM_passphrase = '';

$mail->setFrom("test@example.com", "Test test");
$mail->addAddress("test2@example.com", "test2 test");
$mail->Subject = "Test test";
$mail->msgHTML("Test html html");
$mail->send()

The DKIM key is generated with DKIM_gen_keys.phps.

Thanks :)

[bartkaandorp]

I had the same issue.

It looks like the issue comes from the removing of spaces from $dkimhdrs. That variable is set with "\r\n ", but in DKIM_HeaderC this is removed by preg_replace('/\r\n[ \t]+/m', '', $signHeader)

Because of that there is no space between some of the values in the DKIM signature, so the output hash is not valid.

It is fixed by removing the "\r\n" in the $dkimhdrs or changing line 4357 in src/PHPMailer.php:
$signHeader = preg_replace('/\r\n[ \t]+/m', '', $signHeader);
$signHeader = preg_replace('/\r\n[ \t]+/m', ' ', $signHeader);

[Synchro]

That is not an appropriate fix because it causes problems elsewhere, discussed in #1525.