Trusted-IP SMTP Relay Build
Budget: €30 – €250 EUR
I’m putting together a production-grade SMTP relay that any of our application servers can use without storing or passing passwords. Instead, the relay must recognise and trust specific IP addresses we provide and reject everyone else, so there’s no chance of it turning into an open relay.
Core requirements
• Postfix is the front-runner, but I’m open to another MTA if you feel it better suits the brief.
• The underlying OS hasn’t been chosen yet (Ubuntu, Debian or CentOS are all on the table), so factor in a clean, reproducible install.
• TLS must be enforced for all outbound traffic.
• Each message should allow a custom “From” name and address.
• Once I register the domain, I need full SPF, DKIM and DMARC alignment and the corresponding DNS records so mail consistently lands in Inbox, not Junk.
• Only our whitelisted IPs should be able to connect; everybody else gets a hard fail.
Deliverables
1. Working SMTP service reachable on a standard port, authenticating solely by IP.
2. TLS certificate in place (Let’s Encrypt or similar) with clear renewal steps.
3. Verified SPF, DKIM and DMARC records on the new domain, plus a quick how-to for future domains.
4. Post-deployment test plan showing successful sends from an allowed IP and blocked attempts from outside.
5. Brief hand-over notes or script(s) so the setup can be replicated on another host if needed.
If you’ve built secure relays like this before and can have me sending fully-authenticated mail from my own scripts in short order, I’d love to work with you.
Need help to get trusted-IP
Core requirements
• Postfix is the front-runner, but I’m open to another MTA if you feel it better suits the brief.
• The underlying OS hasn’t been chosen yet (Ubuntu, Debian or CentOS are all on the table), so factor in a clean, reproducible install.
• TLS must be enforced for all outbound traffic.
• Each message should allow a custom “From” name and address.
• Once I register the domain, I need full SPF, DKIM and DMARC alignment and the corresponding DNS records so mail consistently lands in Inbox, not Junk.
• Only our whitelisted IPs should be able to connect; everybody else gets a hard fail.
Deliverables
1. Working SMTP service reachable on a standard port, authenticating solely by IP.
2. TLS certificate in place (Let’s Encrypt or similar) with clear renewal steps.
3. Verified SPF, DKIM and DMARC records on the new domain, plus a quick how-to for future domains.
4. Post-deployment test plan showing successful sends from an allowed IP and blocked attempts from outside.
5. Brief hand-over notes or script(s) so the setup can be replicated on another host if needed.
If you’ve built secure relays like this before and can have me sending fully-authenticated mail from my own scripts in short order, I’d love to work with you.
Need help to get trusted-IP