Question, what if I have to lookup email2 in table4, row3 and email3 in table5, row3 respectively. Rather than adding the email addresses in the expression?
Note that Show_If for a view merely hides the link to the view from the menu or navigation bar. If the user has the right URL–which isn’t difficult to guess–they can navigate to the hidden view and see whatever’s in it. Also, the data used by the view is still loaded into the app. A savvy user can still access loaded data regardless of the lengths you go to to hide it. To secure the data, use security filters to prevent the data from being loaded. In your cases, use the expressions provided by @Arni_Kli in the security filters, too.