• dogs0n@sh.itjust.works
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        2 days ago

        For mail this won’t work.

        For one, you have to now think about dynamic dns because you have your one static ip and then whatever ip your data backup will rollover onto. This isn’t ideal. Probably going to ruin any trust your domain will have.

        Second, there is no way you’re getting a reverse PTR record setup to work in this config.

        So, no, it’s not gonna work (clarification, technically may work, but you are gonna have issues and it’s probably not recommended).

        It may work fine if you have random services, but tbh I don’t ever want to use or deal with a ddns service myself.

        • ysjet@lemmy.world
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          2 days ago

          You do realize your DNS MX records can point to both IPs, and your primary connection just has a higher priority number, right? This is 2025, dns is outright expected to have multiple IPs behind it in varying levels of priority and availability. Just because the cell IP isn’t the active route for LAN-to-WAN traffic doesn’t mean it’s not connected or available for WAN-to-LAN traffic.

          As for DDNS constantly rolling things, I’ve got, as I said, spectrum residential and my IP address has changed once in half a decade, and even then it was extenuating circumstances (I literally moved).

          Finally, I literally mentioned that there were other ways around this, like an external proxy server on a static IP. Throw it on DO or something.

          This is entirely viable for a email server. Would it be better to have two hardwire connections load balanced instead of a primary and failover that’s metered? Sure, if that’s an option in your area, then you just round-robin your DNS. But it still works just fine with a primary and failover.

          Regardless, having two IPs for you email server is absolutely a complete non-issue. That was a solved problem ages ago.

          • dogs0n@sh.itjust.works
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            2 days ago

            Hm, I’m gonna remain skeptical.

            Using the random ip you get from mobile data or using dynamic dns feels risky. Maybe that’s because I’m not smart, but the whole trust level is mail thing seems very heuristical and the risk of damaging my domains trust factor doesn’t seem worth it.

            I’m not skeptical about having two ip addresses, but rather using ones that I don’t have control over (i don’t have the only right to use).

            I might be wrong on the PTR record thing, seems it might be possible with DDNS providers but not 100% sure.