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.






Have you thought about not trying to drag meshtastic down to try and prop ham up?
I get it, you spent a bunch of time studying for your ham and you don’t want it to feel like a waste, but lets be perfectly frank here- most people aren’t going to get a HAM license. It IS, however, VERY accessible for someone to buy a cheap gadget on sale to try out.
I never understand why ham radio people always try to sabotage every other communication method, but you guys do it every time.
Let other people communicate how they want.