I would prefer no to move to a public free service - but I understand that shared hosting doesn't provide the best mail server. Going all the way to run your own vps with your own mailserver seems probably a nice way to go about it, yet adds a lot of work and I am not sure I could charge for such a service to my client. It's not really in the culture to pay for mailserver service. What are people using here on HN? Are there reliable mail server service that make sure not to end up on spam listing, by monitoring the usage before it hits a spam cop site?