How can we create a Push Topic in the Salesforce?

Push Topics are a connection between Salesforce and CxEngage that recognize when there is a new email message in Salesforce and sends that information to CxEngage.

Creating a Push Topic
Go to https://workbench.developerforce.com/.
Select either Production or Sandbox depending on which environment your Salesforce organization is in.
Click Login with Salesforce.Make sure that you log in with the same Salesforce account for the Salesforce organization that you are setting up with the integration.
Go to data > Insert.
For Object Type, select PushTopic.
Select Single Record.
Click Next.
For the PushTopic field values enter:ApiVersion: 35.0
Name: Enter the name you want for the Push Topic.
NotifyForFields: Referenced
NotifyForOperationCreate: false
NotifyForOperationDelete: false
NotifyForOperationUndelete: false
NotifyForOperationUpdate: true
Query: SELECT Id, <Custom Field API name> FROM Case WHERE OwnerID = '<queue ID>'For help finding the API name for the Last Email Received custom field that you created, see Find the API name of a field.
Enter the queue ID for the queue that owns the incoming cases. This is the same ID that you used in the workflow rule.
For example, if the API name for your Last Email Received custom field is LastEmail__c and your queue ID is 00G22000000R4PB, your query is:

SELECT Id, LastEmail__c FROM Case WHERE OwnerID = '00G22000000R4PB'

Click Confirm Insert.