Retrieve messageId of email being sent using ezcomponents ezcMailComposer

Question

I'm trying to retrieve the messageId for the email being sent. I've tried explicitly setting the messageId just before sending, like this:

$mail->setHeader('messageId',ezcMailTools::generateMessageId('example.com'));

I then return the messageId after sending, like this:

return $mail->getHeader('messageId');

... but the counter portion of the Id is always off by one. For example, the return value will be:

[email protected]

... but the actual messageId will be:

[email protected]

Returning the messageId header value without explicitly setting it first returns a blank string. How can I retrieve this value?