Root cause: k3s ServiceLB assigns internal VIPs (10.42.1.x) that are not
publicly routable. External traffic to mail.basicstack.de cannot reach the
SMTP/IMAP services.
Investigation shows:
- Web-UI works (goes through Traefik IngressRoute)
- SMTP/IMAP ports have correct firewall rules
- iptables DNAT rules exist but don't help external traffic
- Internal connectivity works correctly
- LoadBalancer 'external IPs' are actually pod network IPs
Three solution options documented:
A. NodePort + iptables REDIRECT (recommended)
B. Deploy MetalLB for true LoadBalancer IPs
C. Hetzner Cloud LoadBalancers (not recommended, cost)
Awaiting approval on approach before implementing fix.
Related: DEV-235
Co-Authored-By: Paperclip <noreply@paperclip.ing>
