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This might be a bit hard for me to explain - and it is a pretty individual situation.

I got a native server at Hetzner ( The public IP is 88.[...].12. I got ESXi running on this server. I can access the esxi console by the public ip, but none of the virtual machines. That's why I bought a public subnet with 8 (6 usable) IPs (46.[...]) and an additional public ip (88.[...].26). This additional public ip belongs to the first virtual maschine - a firewall appliance - which is connected to the WAN. This need to be done this way - since it is the official way by hetzner. My 46. subnet is behind the firewall.

I got a virtualmin server with dovecot imap/pop3 server. When sending a email, most provider (gmail) will accept those mails, but a lot will put it into spam (aol).

My theory is: The MX line of my domain says of course the ip of the virtual machine (46.[...]), but in the raw email it says that email is sent by the ip of the firewall (88.[...].26), which doesnt sound trustworthy.

A solution would be if the firewall could handle mail, but it simply cant. How can I prevent this problem?


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If you haven't already, you may consider:

  • Setting up SPF record for the domain
  • Ensuring reverse DNS is set up for the firewall
  • Ensuring the static IP is not within a block identified as "portable/dynamic"
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Is the actual ESXi server setup with the required links/trunks/vswitches/port-groups? what you're describing here is far from straightforward, for a start you have 2 different subnets, possibly/probably on different VLANs, how are the links and/or trunks setup for this? what's doing the routing and who set that up?

Basically this appears to be a design, or lack of, issue - have you a diagram of how you expect this to work that we can see plus details of your actual setup. None of this will 'just work' without putting the thought and effort into designing and building it correctly.

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