this post was submitted on 18 Aug 2024
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Email server thru cloudflare (self.selfhosted)
submitted 3 months ago by werefreeatlast to c/selfhosted
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It's a bad title, but I'm trying to figure out how to describe what I want.

First, I got my photoprism working thru cloudflare. Now, on the same domain I would like an email address.

So mysite.com gets routed to 56.654.234.12 let's say by cloudflare such that a global user never sees my ip. But mail.mysite.com that's different, they don't proxy email so if you do a reverse lookup you can find the origin IP.

I heard about tunnels so I stupidly signed up for that, only to learn that a tunnel just lets you into an internal network. So an SMTP server can't get emails from outside that way.

Ideally, somehow I could setup one user at Gmail or proton mail, then somehow setup the same or different [email protected] and I could then use mailu, mailcow, mail docker to house my [email protected] which routes mail thru Gmail or protonmail. I know all this makes little sense because I don't know the proper way, so that's my question for you smart people who have done this twice over. Could someone point me to the best way of setting up a local mail server that routes thru cloudflare but is not easily reverse looked up? Is that even a problem at all?

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[–] [email protected] 0 points 3 months ago (1 children)

The biggest certainty is that just having an open port for an SMTP server dangling out there means you will 100% be attacked. Not just sometimes, non-stop. So you don't want to host on a machine with anything else on it, cuz security. So you need a dedicated host for that portion, and a very capable and restrictive intrusion detection system (let's say crowdsec), which is going to take some amount of resources to run, and stop your machine from toppling over.

I need to call BS on this. No one cares. I’ve been running a small go-smtp based server that would do some processing on forwarded mail for 2 years now and I don’t see much of “attacks”. Yeah, sometimes I get passersbys trying to figure if this is a mail relay, which it’s not.

You absolutely don’t need a dedicated machine and an IDS. And you definitely need crowdsec.

Yeah, sending mail is somewhat hard lately, but DKIM and DMARC can be figured out. Receiving mail is just straightforward.

[–] just_another_person 1 points 3 months ago (1 children)

As is your want to do. I've run thousands of different combinations and type of SMTP related services at all stages of processing, and I've seen the above 100% of the time.

You are talking about receiving mail from another forwarded entity. It's not the same thing. You're also proving my point, because you're already getting your intake handled upstream, so there you go. What I said is accurate. 👍

[–] [email protected] 0 points 3 months ago (1 children)

I won’t quote the bit of your post again, but no, if you have an open smtp port then you won’t get constantly attacked. Again, I have a fully qualified smtp server and it receives about 40 connections per hour (mostly the spam ones). That's trivial to process.

It doesn’t matter that I forward emails from another server, because, in the end, mine is still public on the internet.

If you are trying to make a point that it's tricky to run a corporate-scale smtp and make sure that end users are protected, then it's clearly not what the OP was looking for.

[–] just_another_person -4 points 3 months ago (1 children)

Super cool story though.

[–] [email protected] 2 points 3 months ago

The biggest certainty is that just having an open port for an SMTP server dangling out there means you will 100% be attacked.

True.

Not just sometimes, non-stop.

True

So you don't want to host on a machine with anything else on it, cuz security.

I don’t think "cuz security" is a proper argument or no one would be ever listening on public internet. Are there risks? Yes.

So you need a dedicated host for that portion

Bullshit. You do not need a dedicated host for smtp ingress. It won’t be attacked that much.

and a very capable and restrictive intrusion detection system (let's say crowdsec), which is going to take some amount of resources to run, and stop your machine from toppling over.

That's not part of the mail pipeline the OP asked for.

Here, I brought receipts. There are two spikes of attempted connections in the last month, but it's all negligible traffic.

Self-hosting mail servers is tricky, same as self-hosting ssh, http, or whatever else. But it's totally doable even on an aging RPi. No, you don’t need to train expensive spam detection because it's enough to have very strict rules on where you get mail from and drop 99% of the traffic because it will be compliant. No, you don’t need to run crowdstrike for a server that accepts bytes and stores them for another server (IMAP) to offer them to you. You don’t even need an antivirus, it's not part of mail hosting, really.

Instead of bickering and posturing, you could have spent your time better educating OP on the best practices, e.g. like this.