Connecting MailServer to compiled onlyoffice groups

I have successfully compiled onlyoffice groups in a windows server, and the basic functions are working smoothly. But I have an issue whilst running the mail server. Since it has to be done separately, I have set up the mail server separately using docker. I used the command: bash -ics false -ids false -icp false -ims true -md -es true . I modified the A-record of the domain I was using as well and tested it. But I came up with connection errors while trying to connect. Here are the current setting I have applied and the error message that I am getting:

Any advice on what I have done wrong here? Also please note that I have used a compiled version of the onlyoffice groups.

Hello @BimsaraM
Please double check mutual availability between server via wget\curl command. Are servers accessible to each other? Additionally, please go to the Mail server and run docker ps command, please show us the output result and point us to the guide that you used for Groups compiling as well.