TYPO3 Core

Since ver. 4.2.2 I have two semicolon in a line of the mail-header in multipart-mails.
This line in received mails is now "Content-Type: multipart/related;;".
Therefore some spam and virus filters doesn't accept this mail.

Maybe the solution is the line 566 in class.t3lib_htmlmail.php (new in ver. 4.2.2):
565 // Generate plain/HTML mail
566 $this->add_header('Content-Type: ' . $this->getHTMLContentType() . ';');
this line adds a semicolon, but in 533 comes already a semicolon with the value.
533 public function getHTMLContentType() {
534 return (count($this->theParts['html']['media']) ? 'multipart/related;' : 'multipart/alternative;');
535 }
After deleting this semicolon in 566 everthing works fine, but I don't now, if I get other problems with this solution.

(issue imported from #M9612)