There are a number of reasons for that: he may have deleted it, it may have been destroyed as spam, or something may have gone amiss.
Either way, the only people that can tell for sure are the admins, and you need to ask here:
http://www.codeproject.com/suggestions.aspx[
^] not in QA.
WHen you do ask, give them all the info you can: link to the article, and a copy'n'paste of the email you got telling you the message was posted would help.
Who posted the message? Do they still exist as a member?