Talked with adobe consultant, and it is not the usecase to setup /etc/map configuration on an author instance.The issue should be resolved by setting up a proxy server, that listens on example: www.externalDomain.com/content/consumer_elec/b2c/europe/nl_be/index.html and setup a rewrite on that URL to www.externalDomain.com/nl_be/index.html.So the customer will not see the absolute URL directly.

Hi,This is a bug on Campaign side which has been fixed in latest build 8886.Please reach out to support to get the instance upgraded (if you are hosted) or request for the build and perform the on-prem upgrade.Regards,Vipul