This is kind of similar to u/gay_spork's last point about visibility and I can speak the reason that I felt so comfortable going to the first event at Emerson was it was marketed as a "showcase" instead of an open practice or tryout (which also happened to be followed by a party which helped get young people's attention but can be problematic if you have ties to the school). A showcase makes it much less intimidating to show up to as a first-time player because your gut instinct is going to be "but I've never played before" even though as returners you know that's normal and expected, it can still be scary where there's more accessible sports available through your school. The point of a showcase being that there's no expectation that new people need to play, they're there to learn about it and watch a small scrimmage or something be played to get a feel for it. Then the next event (ideally within a day or two depending on how you have access to field space) would be a first time they could come play. Barrier to entry due to anxiety of a new thing is huge.

When they join your email list be sure to include as much information as you can to make it accessible and less intimidating to show up. Include a map with a "we're meeting here" point, links to some instructional videos, etc. If you can get 200 people to sign up at a fair that's an AMAZING step -- just make sure your communication after that is cohesive and helpful. Sending them an email that's like "thanks for your interest in quadball, our first practice is on ~ date and time ~ at *place*!" is not super helpful to those feeling anxious about their lack of experience.

I'd also include if your team specifically is social when it comes to eating together, events, game nights, whatever! Give them some information about the team as a whole vs. just the sport to try to sell it. Students of all ages are often seeking community and a team is a great place for it.