Agreeing to receive daily spam in exchange for the chance to send out some spam yourself? How will you protect yourself against bots? Any chance you can do "groups" with a bit of targeting? It might be easier to win the lotto and you have more chances of the people receiving the message actually being interested in it.
Haha hopefully not too much spam... Regulating bots is a good point though. Right now the app is only accessible on a phone, and only one message can be submitted per phone (based on unique phone ID, not user name) per day, so that should limit it some. However, if this becomes popular I will definitely need to code some countermeasures for bots. I think groups is a really cool idea. I am programming this in my free time for fun, but have a running list of improvements, I'll definitely add this. Thanks!