I'm not sure the EC's know on the 15th; I think they get an email several days later. And I don't think you should call your EC. It's obvious that although MIT could let you know through an email or have you log on and find out online (as many schools do), they want to send your decision in the mail.
trust me, there is nothing as gratifying as opening your mailbox and seeing a big envelope with MIT on it. As stressed out as I was that week waiting for it, I wouldnt have wanted to find out any other way.
So would I. Or ask someone considerably braver/less invested to open it and pitch it if it was "reject", and tell me if it were "defer". Any MIT people who might possibly be watching, please don't do this. It isn't funny.
That kinda violates the "first of all, do no harm" rule...'Especially because I wouldn't necessarily look at the signature. But saying that they lost the application information, a la the technical glitch, would be okay, I think...
My EC told me about a hack he and his friends did in the sixties where they hijacked a steamroller from an unguarded construction site and drove it along the steets of Cambridge to the president of harvard's front lawn. Apparantly the headline in the paper the next day was, "Prez's Peonies Pummelled" or something of that nature.