I have been playing around trying to setup an SMTP server that will accept incoming mail to be delivered to local users from both localhost (figured out) and remote servers (not figured out) as well as send mail to other servers from authenticated SMTP users connecting to the mail submission port (not figured out) without becoming an open relay that will be taken advantage of for spam (the reason I am trouble figuring things out). Can anyone help me with this? I am using sendmail as the SMTP server and the POP/IMAP is running through a different program and has already been set up and works.

Thanks.

Sounds very doable. I'm still a bit confused about at which point you're stuck, even though you put in a lot of details there. Is the first problem that authenticated SMTP is not working to accept incoming mail for forwarding?

There are several points I am stuck on maybe that is why you are confused, I can get localhost to send messages to the server just fine and they are accepted, the issues are getting the server to accept mail from other mail servers and deliver it to local users and getting the server to relay authenticated SMTP users mail to anyone but I have to have it do both without allowing non authenticated users to send mail to anywhere, they can only send to local users of the server.

May I ask why you're making your life difficult and not just requiring all incoming mail to be authenticated?

I thought i needed to accept unathenticated mail on port 25 for me to receive mail from users on other servers. Public mail servers like gmail's would not have an account on my server and I want to be able to recieve mail from them

Sorry, but most ISPs block SMTP from home connections and most email servers automatically flag them as spam anyway. In other words, you will be seen as a spam server regardless of how you set it up, so you might as well be an open relay.

One issue with your logic, this is not being run at my house, this is on my VPS at a hosting company where I can change the rdns and have, the rdns is mcgurrin.net and the mail would mostly say from user@mcgurrin.net so most would actually not flag it as spam from any of that, the bigger issue than being marked as spam for me is actually TOS violations and loosing my VPS.

Oh, that makes sense. :/ To be honest, I haven't run into that particular setup issue before

Yeah, I think this is not a common issue because I think they are often separate servers but right now I don't have another server I can use so I need to do this on one server.

Ah, well, I still can't imagine that it's so challenging as to be impossible. In fact, I'd expect something that works well bridged across two servers to be even more straightforward with a single server.

I'm pretty sure it's possible but from looking at the configuration it is actually much easier to do it on one, you set the incoming mail server to relay to no one and accept unauthenticated and the outgoing to relay to anyone and only accept authenticated connections emails.

I guess so, that makes sense. If worse comes to worse, surely you could fake it with two instances of the mail daemon, two virtual interfaces, even two physical interfaces if it came to that?