When using "not equal" conditions, a sharing rule operates on an opt-out basis, meaning that the sharing occurs unless certain conditions are met.

As a best practice, especially when sharing CRM data with external users, one should always define the sharing scenarios the other way around, keeping data private as a default and then defining the sharing criteria on an opt-in basis.

This rule detects validation rules that use a "not equal" condition to share data with external users (guests or portal users).