Not sure, but I'm having the exact same problem.  The browser said the code was processed and to check my inbox, but nothing so far.  (I used the GETDEMYTHA26 code).

Just to check I tried to use additional existing player promo codes in my open game, and it simply didn't respond.  No "expired" or "already used" message.  Just...nothing.

Most of those code are for brand new players to the game. if you want them you will have to delete your game and plarium and add a new email address to get that new code to work 24 hrs into making your new acct use it