Ask HN: What Mail Server Do You Use?

Hey Hackers,

I am looking to move some of my personal projects and portfolio site from WebFaction over to DigitalOcean. Right now I use WebFactions mail servers for a few of my custom domains.

And was wondering what you guys use for mail servers. Do you use a hosted mail server, or do you host your own? Free, Paid or open source? Any recommendations for a small scale email server to use?

Thanks guys!