For another paid SMTP solution, Amazon's SES has been bulletproof for me. They also really grill you on what purpose you intend to use it before letting you in. My mail volume is so low I still haven't seen a bill.
I was tempted but had an AWS runaway 5-figure bill at work once - I think someone forgot to shut down an EC2 instance - which has scared me from using them for personal projects. I heard they're usually understanding in those situations and have features to limit your bill, but that feels like overkill for personal email.