I'm hosting an academic competition, and I need to get the word out to any peers that may be interested in participating. My advisor told me to search for academic mailing lists, but I can't find any. What are the best venues to get the word out about academic information? I'm particularly interested in publicizing the competition throughout the USA and Brazil, but any advice is warmly welcomed.
Clarification: My objective is not spamming or any kind of malicious activities. The same way that conferences and activities are spread by someone inside the universities, I would like to reach to reach a wide audience to invite them to participate in the competition, with pure academic interests---specially since the competition is part of an international conference.
The topic is related to machine learning. But any tips for any kind of topic are welcome.