Transfer Tool fails to copy Greylist configuration; "The system failed to trust any IP addresses"

Symptoms

In some scenarios, the Transfer Tool may fail to copy and restore the Greylist configurations between the two servers in your transfer. The log may return this error:

Starting “RESTORE” for “GreyList” “GreyList”.

Failed: (XID 7p5swg) The WHM API v1 call “cpgreylist_trust_entries_for_common_mail_provider” 
failed: The system failed to trust any IP addresses.

Description 

This error is commonly shown when the Greylisting list of common mail providers is empty. Additionally, enabling Greylisting does not automatically add the common mail providers to the list. If this is the case, it is easy and safe to rebuild the list of common mail providers.

Workaround

Use the below command to add the common mail providers to the Greylisting list:

/usr/local/cpanel/scripts/manage_greylisting --update_common_mail_providers