You wrote a script that finds hiring managers and emails them about your candidacy. It worked for a week. Then the replies stopped, and you assumed nobody was interested. Nobody was reading. Somewhere around email 80, Gmail started filing you under Promotions, and somewhere around email 200 it started filing you under Spam. Your open rate did not drop because your message got worse. It dropped because your cold email deliverability did — the sender reputation that decides whether a message re...