Popularity of the ebook totally surprised us. 700 downloads in 30 minutes killed gmail. We're working on the problem right now. In about 10 minutes, we'll post links to download on the landing page.
My sincere apologizes!
app doesnt scale , that's a poor user experience , use a webservice like mailgun or sendgrid at least ...
We've switched to mandrill. Cheers! :)
google apps and gmail has a 500 per day send limit - try a service like sendgrid or mandrill instead, I think most of them have a free tier.
I got that too, and have not seen an email after 5 minutes.
See mtreder's reply below, for a download link. According to Twitter they're having some email issues.