

The big problem you’ll run into is that it’s very likely outgoing connections to port 25 is blocked. In my experience it’s very uncommon that residential ISPs allow it, and even most VPS providers will block it unless you request access. So you’ll most likely need some form of relay anyway, and at that point you may as well send directly to the relay.


To be honest I haven’t done that deep search into how common it is for VPS providers to block port 25, but in the cases it has been relevant for me it has required at least raising a request and for instance for Hetzner being a customer for at least one month. I’ve figured that it’s a good thing and if a VPS provider has no restrictions at all their IP ranges are much more likely to have bad reputation and blocklist issues.