connection refused to a domain on another virtual machine

Hi there.

First i want to explain the situation.I have 2 virtual machine.

• VM1: have 1 public IP pointing to 192.168.0.30
• VM2: have 1 public IP (diff from VM1) pointing to 192.168.0.34.

I can send emails to yahoo, gmail, etc, doesn't matter where, everything work, but if i want to send an email from a domain on VM1 to another domain on VM2 the connections is refused, cannot send it. This situation happen in both ways(VM1 to VM2 also VM2 to VM1).

I look in the mailog and i only got 1 msg "connection refused".

I don't know what to add or put so i can send emails from VM1 to VM2 and vice-versa.
Any ideas?
thanks in advanced

Forwarding on a standard router can only forward port 25, 465, 587 to 1 machine, and then has to be able to communicate back out via that same port.

rDNS has to be correctly setup as well as DMARC, DKIM, SPF and not to mentioned SSL or MTA-STS.

Pointing 1 public to a VM is good for test and learning.
But if you going to use these as a production server, they each need public IP's, not behind a NAT.

Using a NAT isn't going to get support from anyone really, since every router can be configured differently.

Thanks for your reply.

Basically i have an IaaS (Infrastructure as a Service) where i can make VM, VPN, etc.
IaaS managing for me DDOS, mirroring servers, back-up space, etc. (at a big lvl)

On that console i set the network adapter for in/out from public IP to private IP in any direction with any port, so not using the NAT ip from CentOS WebPanel.

rDNS is set for the main domain and IP of the server.

I also set Dmark, SPF, DKIM, based on the several online tools, my email server is set correctly.

I can send emails for any other domains that are outside my VM (gmail, yahoo, ymail, etc) and everything is working like a charm.

I ran into a similar problem when i try to curl from VM1 to VM2, i added in /etc/hosts the domain with the local ip and curl work perfectly. I'm wondering if i have to do something similar.

Also 25, 465, 587 are open both direction, do i need to add in some conf file the same option like i did in /etc/hosts?

Check the mail logs to identify where your VM tries to connect to when you send emails from VM1 to VM2. Make sure the MX records of the recipient's domain directs emails to the correct host.

What does happen when you run

Code: [Select]

telnet MX.HOST.COM 25
traceroute MX.HOST.COM
(MX.HOST.COM - mx record of the destination mail domain)

on the source mail host ?