I assume you didn't read the fine print on the posting about getting the emailed code for playing Halo 4 online before the 20th to receive the 6 other specializations.
No problem its a simple mistake and its obvious not many people actually looked at the fine print, LOL then again its like reading a game or electronics manual, who does right? lol, well I always do so....Please allow me to explain this matter further to you so that it may hopefully clarify this issue.
Now we all know limited edition buyers like myself got a DLC exclusive code to see 6 extra specializations on-top of the original 2 standard users are only able to see for the time being. But us Limited Edition buyers still had to rank up to be allowed to choose 1 out of the 8 instead. As where Standard Editions only got to choose between 2 at the time.
Now, Shortly before the Launch of HALO 4 Microsoft and 343i released a news update on the Xbox dashboard. The one you are in question about. The tab you are talking about said if you play Halo 4 WAR GAMES matchmaking online anytime between the November 6th and the 20th of November you will unlock the other additional 6 Specializations for Halo 4 bringing the total to 8 choices rather than 2.
HOWEVER, what most people like yourself missed was the small print beneath the message on the tab. If you would have read this you would understand why you have yet to receive the content code for the specializations.
THE CODES WERE NOT GOING TO BE RELEASED ON THE 20th OF NOVEMBER,
The codes are to be released on November 30th by email containing a code for the 6 Specializations.This delay rather than being instant is to allow 343i and Xbox to gather the amount of Standard edition users emails and gamer-tags who participated in this promotion. After that they will then send the codes VIA email for you.
Below I have copied and pasted the exact words from the Tab about receiving the code and this promotion:
You must play Halo 4 SE by 11:59 p.m. EST on November 20. After that, "A download code will be sent to the email address associated with your Xbox LIVE account by November 30, 2012."
Hopefully this clears things up and will get rid of any confusion, Any questions you can message me on XBL, my GT is VAUZIX. Hope I was able to clarify and help out.