RoundCube Sends but will not receive.

Hi
I hope you don't mind me jumping on this thread. . .
I'm experiencing the same problem. I have just obtained two VPS servers, both of which are running CentOS 7.3.1611 and I've installed Centos Web Panel on both. I'm currently using the bundled Free DNS Manager to manage the DNS zones.
On one of the servers (goodserver . com), I can send and receive emails without any apparent problems, but on the other (badserver . com), I can send emails, but I don't receive some emails.

Using Roundcube with me[at]badserver . com, I receive emails sent from me[at]badserver . com and I also receive emails sent from me[at]goodserver . com.

goodserver . com is a separate VPS with a different ip address to badserver . com. But I don't receive emails sent via Roundcube from me[at]myotherserver.com which is a managed package on cPanel. All three servers are from the same hosting company.

I've compared the DNS records (held in Free DNS Manager) for goodserver.com and badserver.com, and apart from domain name details and ip address, they are exactly the same (domain name and ip address are both appropriate for the relevant server.

netstat and iptables output is the practically the same for both servers and is:

tcp 0 0 0.0.0.0:smtp 0.0.0.0:* LISTEN 1887/master
tcp6 0 0 [::]:smtp [::]:* LISTEN 1887/master

Chain INPUT (policy ACCEPT)
target prot opt source destination

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination​

On goodserver.com, the number is 24672 as opposed to 1887.

Any suggestions or pointers would be most gratefully received.
Many thanks

 

i created an email server and we everything works fine on the server but roundcube is able to send emails but not receive them.Below i am giving my netstat info.

 

CHAIN INPUT and CHAIN FORWARD shows Policy DROP