I’m aware most ISPs do not allow for port 25 to be open for email use outside of business licenses, but at what level is that controlled? Can I get around that by owning my own router? Owning my own modem or ONT? Or is this just a thing they mystically control further up the pipeline that a relative layman such as myself can’t get around?
We do that upstream, no way for you to avoid it. For good reason too, our team handling abuse notifications mails was super swamped with people whose ancient XP PCs had malware sending spam.
Forget running your mail server on a residential IP anyway. You’ll be instant blocked by any mail provider, residential IPs are always spam, because of the aforementioned XP PCs.
Personally I wouldn’t self host mail anymore anyway. Too much trouble.
Your ISP controls what ports you can access using one or more firewalls and traffic control devices somewhere past the point where you connect to their network.
They can block whatever ports they want. The only way around this is to use a VPN, which creates a tunnel directly from your device to a remote server to route traffic. This still goes through your ISP and whatever firewall they have but does so over a port that they (probably) don’t block. They can’t see what ports your web or network requests are using so they can’t block it directly.
Depending on your technical know how and what type of router you have, you could set up a VPN at the device level (PC, phone, etc.) to send just requests from that device or at the router level which could send all traffic from your network through the VPN.
It’s important to remember when using a VPN that the VPN servers can still see (and potentially log) all of your traffic, even if your ISP cannot. You still need to find a VPN service that you trust to not monitor your traffic.
I’m not terribly worried about a service seeing my traffic, the initial concept was for a self-hosted server to run a business email and site and some tools on, but I can’t do email through my ISP without paying an arm and a leg, and my business doesn’t make enough for that…
It’s all on their end, though I’ve had limited success asking nicely, it’s just there so businesses don’t just order the cheaper plan and then they have to deal with all the extra traffic and support for many users. Just assuring them that I am just running as a single user my own email server they were cool with it on small local ISPs bigger corps won’t give you the time of day on that issue.
I’ve been running my own mail server using Mail-in-a-box on a digitalocean VPS for about 10 years. I also pay for an external SMTP relay service because I still get randomly blocked by Google/Microsoft/whatever just by virtue of having a digitalocean IP.
Total cost is $15/mo for the VPS and $50/yr for the relay service.



