Overrides TextPart::getPreparedHeaders
public function getPreparedHeaders() : Headers { $headers = parent::getPreparedHeaders(); if (null !== $this->cid) { $headers->setHeaderBody('Id', 'Content-ID', $this->cid); } if (null !== $this->filename) { $headers->setHeaderParameter('Content-Disposition', 'filename', $this->filename); } return $headers; }