Mailing List Question

<p>Last year I made an account on MIT's website so that I would look at the app. By doing o I thought I was singning up to be on the mailing list as well. Since that was more than a year ago, I am wondering why I got mail from MIT last month. On the mail they sent me was a code so that I could sign up to be on the list. I am curious as to why MIT sends out these special codes for lack of a better term. Why not just send mail when people sign up in the first place?
Also does anyone know when MIT will send out more mail? (on the thing they sent me it sai more was to come :P)</p>