This. Absolutely this. Considering hosting your own service involves paying a competent system administrator at least $75K/year in addition to buying hardware a

This. Absolutely this. Considering hosting your own service involves paying a competent system administrator at least $75K/year in addition to buying hardware and network and power, $5/user/month is more than reasonable for such an extremely high level of service. If some mission critical email was delayed for a little over an hour, pick up the phone. This is the very definition of a mountain out of a molehill.