While $19 yearly is admittedly very cheap, 20 daily outbound emails seems like an absurdly low limit. I can't imagine many sole proprietorships (as they suggest as customers for that tier) would be able to sustain that.
Especially since most email providers count a single email addressed to 10 people as 10 emails. Get into a back and forth discussion with a moderately sized group and you'll hit your limit after only a few messages.
