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Hello good people,
We have a bit of a strange problem that we were hoping someone here could help us with.
We provide basic website and email hosting for micro businesses. We have a Virtualmin server which hosts about 30 clients, each with their own domain.
The server is self hosted and behind a firewall, which does NAT and port forwarding.
We make use of DDNS with a dynamic IP address for the public IP, which works perfectly for us except that we dont have a reverse-IP lookup.
Unfortunately this means many legitimate emails end up being marked as spam.
To resolve this issue, we thought of using our dedicated email server, which is hosted at an international ISP, as an smtp relay for sending emails from the virtualmin server.
How would we set up the Virtualmin server to relay to the main server?
What would need to be set up on the main email server to accept and relay these emails?
Would this solve the reverse-ip lookup problem?
In case anyone thinks we are gonna be spamming etc…
Our clients are mostly very small businesses or community interest groups, who cannot afford big monthly costs.
Our virualmin server is hosted in Africa, where internet bandwidth is extremely expensive, which is why we are using self hosting with DDNS. (The same bandwidth with a fixed IP is 10x more expensive, as is ISP hosting).
Very congested international bandwidth means hosting websites in Europe or USA is a no go, as the performance is horrible for local users.
Email (together with Whatsapp) is still the most commly used way to keep subscribers up to date with local events
Some mailing lists can get quite big (one already has 50k subscribers) so using the free smtp relays isnt really an option for them.