I am not sure what you mean by emailing them? It's not like DYS. If they receive valid test scores from College Board, then you are in. There is no decision. JHU SET emails you the invitation with questionaires. You accept or not by returning the questionnaires. The invitation came within days of release of scores by the College Board. We sat on the invitation for two months (lazy/busy), but once we sent back the questionnaires, another welcome email with links came within a couple of days. The hardcopy Imagine magazine along with another publication (SET members) came by mail 2-3 weeks later.
