I have been struggling with a situation with connecting to an external mail server for years (!) now. I have turned on all of the logging that I can think of with our Astaro 220 in an effort to nail down this problem, but I haven 't found anything yet.
I have tested DNS with a ping mail.problemdomain.com, and it resolves the IP address correctly. The ping fails (as it probably should) and the response from the ping is "Reply from 192.168.1.1: Destination host unreachable." The 192.168.1.1 is the address of our Astaro 220, which I assume is normal.
From my Astaro protected network, I cannot telnet on port 25 to mail.problemdomain.com and I get a "connect failed" message. When I go to our backup internet connection, or from my home connection, I can telnet and connect to this domain.
I have added a packet filter on my Astaro at the top of the list that allows my computer to send to this domain on any port, this domain in both directions on port 25, and various other packet filter defeating settings. I have increased the logging in this area, and the requests on port 25 to this domain are shown as being allowed.
It looks like whenever the source is our public IP, or when the requests are being routed through our Astaro 220, this domain is like a black hole to me. I have been in contact with the IT folks in control of this domain, and aside from having trouble with them responding, they have reviewed thier setup and do not see anything that could be causing the problem. I had assumed that we had somehow become black listed, but I have tried an additional IP address on our DMZ on this same Astaro and it is also blocked.
This has led me to believe that either the Astaro is somehow blocking this and I can't find the right logs to see why, or the domain admins of the other domain are black listing us or have a configuration issue of some sort.
I am at a loss at how to proceed, and would welcome any suggestions for trying to fix this.
Thanks!
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