how to submit follow up bug reports?

I often use the unity bug reporting tool when I believe I have discovered a bug or a mismatch in behavior etc but I was wondering if there was a official way to submit follow up reports to a previously reported bug? The fogbugs reporting system does not seem to allow this.

You reply to the email that you received containing the bug number.

Graham has it right. Guess I should take more time to read all the email. I always skim over it and delete them. The last line of the email reads “Please reply to this message if you have additional information you think could help us resolve this issue.” /facepalm