this solution not fixed my problem.
I listed ascii code from $subject:
"Your registration confirmation (mydomain.org)
last char in $subject is 10 ascii code, after ")" and this sign generate problem.
In htmlMineMail.php I added before send function:
$subject = preg_replace('/[[:cntrl:]]/', '', $subject);
and mails confirmation are delivered.
I don't have idea, why sign #10 adds on end $subject.