core-bundle/src/Resources/contao/library/Contao/Email.php
public function attachFileFromString($strContent, $strFilename, $strMime='application/octet-stream')
	{
		$this->objMessage->attach(new \Swift_Attachment($strContent, $strFilename, $strMime));
	}
public function attachFileFromString($strContent, $strFilename, $strMime='application/octet-stream')
	{
		$this->objMessage->attach(new \Swift_Attachment($strContent, $strFilename, $strMime));
	}
Attach a file from a string

@param string $strContent  The file content
@param string $strFilename The file name
@param string $strMime     The MIME type (defaults to "application/octet-stream")