e-Newsletter not Saving or Sending

I am unable to send or save newsletters with eNewsletter.

I have disabled all other plugins, changed to the default theme and it still won't save or send.

I am using SMTP
Hosted on IIS 7.5 with MySQL 5.5.29 and PHP 5.3.18

The only thing I am able to do is send a Preview email from Create Newsletter > Preview so the SMTP settings must be correct.

Any ideas?