Original plaintext body not available to hook_mail_alter()

In hook mail alter you can access mimemail's HTML body text in the following versions:

• Processed: $message['body'][0]
• Unprocessed: $message['params']['context']['body']

With the plaintext body however, you can only get:

• Processed: $message['params']['plaintext']

This is because the variable is processed in place.

It would be good to be able to access the original plain text also.