No matter what I did, Joomla sent all mails correctly and CB did not. There's a lot of threads trying to deal with this.
I finally found the missing line in SMTP handling. My host was configured as localhost without security or authentication.
In the file:
Code:
/libraries/CBLib/CB/LegacyComProfilerFunctions.php
Find and adjust the lines to clear a single value, which otherwise remains default "1", and blocks proper SMTP working in my case.
Code:
..
if ( $smtpsecure === 'tls' && substr( $mail->Host, 0, 6 ) !== 'tls://' ) {
$mail->Host = 'tls://' . $mail->Host;
} else {
$mail->SMTPAutoTLS = false; /* THIS ELSE BLOCK WAS REQUIRED */
}
..