If your email reliability is affecting you financially maybe you should pay for a pro account?
I would NEVER use a "free" service for e-mail if I depended on it for $
This is a lesson well learned for you.
i am paying sendgrid. i'm not using the "free" service either. Pro is 8x the cost i'm paying now. mandrill was the same price and actually delivered email. go figure. and i'm equally pissed at the horrible level of customer service as i am at the quality of the actual service.