Remove Watermark from email body of incoming emails

We get emails from third party vendor servicenow instance to my client instance related to vendor incident and service requests. As soon as the email hits the client instance, a call record has to be created. I configured an inbound email action for this but the incoming vendor email has watermark because of this my inbound action is not triggered and the email is getting ignored. Could anyone please let me know the script to remove watermark from email body.

I referred this post: https://community.servicenow.com/community?id=community_question&sys_id=bb064b61db1cdbc01dcaf3231f9619a6 but I am not sure on the code of how to remove the watermark from email body.

So any scripting help on this is really appreciated.