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Email Fails From One WHM server to the other (and vice versa)

chrisdhall
So here's a strange one for you.... This is an ongoing problem we have had for months now. We have two cpanel/whm servers. The servers are supplied by the same data centre. They are seperate from each other with their own batches of IP addresses. Now the problem is: if client A on server 1, tries to send an email to client b on server 2, then the message is rejected. if client b on server 2, tries to send an email to client a on server 2, then the message is rejected. I say rejected, it actually times out. client a and client b can send to any other server on the internet, but it will not send to the WHM servers under our control. This is not for just a single account/domain - this goes for ANY domain account trying to send from one to the other. Below is the time out message (email address edited for privacy) Event: defer warning User: hypadjco Domain: xxxxx.co.uk Sender: xxnion@xxx.com Sent Time: Aug 6, 2014 1:59:13 PM Sender Host: HCSANDY Sender IP: xxx.xxx.xxx.180 Authentication: dovecot_login Recipient: xxx@xxxxxers.com Delivered To: Delivery User: Delivery Domain: Router: lookuphost Transport: remote_smtp Out Time: Aug 6, 2014 2:28:14 PM ID: 1XF0oe-0002po-1W Delivery Host: Delivery IP: Size: 10.31 KB Result: Connection timed out
The PTR's seem fine for both the servers: PTR mail.domain.co.uk 120.154.xxx.x and PTR mail.domain2.co.uk 232.148.xxx.x
We really are stumped. We've checked the firewalls, disabled IP tables, added the IP addresses of the servers to the various whitelists, but to no avail. We'd be really grateful for any help or a point in the right direction. Chris

Comments

5 comments

Date Votes
  • cPanelMichael
    Hello :) Are you able to telnet from one server to the other over port 25? EX: telnet 1.2.3.4 25
    Thank you.
    0
  • chrisdhall
    Thanks for the response Michael. Seems something strange is going on. If I try and telnet from server 1 to server 2 on port 25, I get this: # telnet 62.164.181.82 25 Trying 62.164.181.82... telnet: connect to address 62.164.181.82: Connection timed out telnet: Unable to connect to remote host: Connection timed out
    However. If I run a port checking tool on the IP address, it tells me the port is open /http://www.yougetsignal.com/tools/open-ports/ Open Port 25 is open on 62.164.181.82. If I try it the other way around, I get the same thing Port checker says: Open Port 25 is open on 86.54.110.226. Telnet says: # telnet 86.54.110.226 25 Trying 86.54.110.226... telnet: connect to address 86.54.110.226: Connection timed out
    0
  • kernow
    I can confirm that telnet works for both IPs, we were able to connect without error. Is any comunication possible between the two servers? is ssh working?
    0
  • cPanelMichael
    I suggest posting the telnet output to your data center so they can ensure there are no firewall/router rules blocking the connection attempt from the network level. Thank you.
    0
  • chrisdhall
    [quote="kernow, post: 1722031">I can confirm that telnet works for both IPs, we were able to connect without error. Is any comunication possible between the two servers? is ssh working?
    Thanks for your responses, and thanks for trying to telnet in yourself - that gives me some ammunition to use with the data centre. I will update this thread when I have more news.
    0

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