I’m going to start off but saying I know that self-hosting email can be a bad idea. That being said, I’m trying to de-googlfy my life and would like to experiment.
I have a VPS and a domain that doesn’t get used for much at the moment. I’d like to try configuring a full mail suite on that domain and see if I can make it work. I’ve been looking into the various options on this list and was hoping for some feed back on options that people have used. If this works out it would be fairly low volume.
Ideally I’d like a full solution that includes web administration if at all possible. I think I’m leaning towards mailcow but it might be overkill.
I’d appreciate any input on what has or hasn’t worked for people. Thanks.
Short answer, likely yes. It’s not definitive, you could still slip by after sending enough mail, but you are also very likely to get whacked because that VPS IP doesn’t have an email sending reputation.
Longer answer, email gateways like Google, Microsoft, and Proofpoint don’t really care who owns what IP. Well, they might, but they’re more concerned about the sending habits of an IP. While you might send good mail from that IP, there’s no reputation for it, so you could be whacked for having a neutral reputation (the ol’ credit score dilemma but for email).
In order to have a good reputation, you have to send a large volume of messages very gradually over several weeks to “warm” your IP as a reputable sender. I went over this slightly more in detail in another reply, but this article is pretty concise on how an enterprise accomplishes this with a dedicated IP at a provider like SendGrid: https://docs.sendgrid.com/ui/sending-email/warming-up-an-ip-address