Hi Willy,
In order to change which default tab link customers are sent to you must make a copy of the stock CRM_ListBuilder screen and customize it, then modify the specific actions in the Process button(s) which are related to the portal link. The link urlforportal is just a placeholder until the actions in the Process button(s) work their magic and the email is sent. If you currently have a custom ListBuilder screen I would suggest you delete it and make another one, other wise just perform my suggestion and it'll work as intended.
If you don't understand how to perform what I suggested, I would recommend watching our Customization Webinars in order to get a better grasp on the how-to's. Just scroll down to the Customization section. Alternatively you can always get training or customization help from one of our Consultants or Method Solutions Providers, however these are paid sessions.
- Ashur