email trigger - email not sent on the user

I'm using private cloud free trial so I'm limited to two users. The two users have the roles: Admin, and Collector, respectively. I have 3 objects, let's name it Object1, Object2, Object3 for simplicity. Object1 has a relationship with Object2. Object2 has a relationship with Object3 but Object1 does not have a relationship with Object3. When a new record is created in Object3, it triggers a trigger in Object2 that will trigger a trigger in Object1 that will send an email to the two users about Object1's content . When the Admin user creates a record in Object3, the trigger works and the email is received by both users. The problem is when the Collector user creates a record, both users does not receive the email. The Collector user is only allowed access to Object1 and Object3 (and two tabs only seen).