/**
* Adds a message header.
*
* @param string $header The header name.
* @param string $value The header value.
* @param boolean $overwrite If true, an existing header of the same name
* is being overwritten; if false, multiple
* headers are added; if null, the correct
* behaviour is automatically chosen depending
* on the header name.
*
* @throws Horde_Mime_Exception
*/
public function addHeader($header, $value, $overwrite = null)
{
$lc_header = Horde_String::lower($header);
if (is_null($overwrite) && in_array($lc_header, $this->_headers->singleFields(true))) {
$overwrite = true;
}
if ($overwrite) {
$this->_headers->removeHeader($header);
}
if ($lc_header === 'bcc') {
$this->_bcc = $value;
} else {
$this->_headers->addHeader($header, $value);
}
}
