Our Exchange Server's IP address appears to be blacklisted. Whenever emails are sent to specific domains they get delayed and eventually bounce back. I have tried to do an SMTP connection to the MX servers used by these domains and the connection times out. However, if I make the same connection from a different server on our network the connection is successful.
These are the MX servers I am unable to connect to:
Do you know what spam lists these MX servers use and how we can remove our server's IP address from them?
Also, is it possible to shorten the length of time an email tries to be delivered before an NDR is generated?