We used to manage the setup ourselves (spf, domainkeys, bounce tracking etc), but switched to Sendgrid (http://sendgrid.com) for all our outgoing e-mails a couple of months ago. Delivering around 600k e-mails/month. Delivery has been great, and we haven't had to spend hours of troubleshooting and managing our own outgoing mail servers. The Sendgrid management interface is OK, but could be better.