Troubleshooting Email Access in RB2B and Apollo Integration

Hello - I’m using RB2B to identify companies who visit our key pages and then I filter by firmographics (e.g., company size, industry, etc.). The part I’m stuck on is then getting emails from contacts of the ICP. While I’m able to find them using our Apollo account connection, I’m not receiving emails, they return as: email_not_unlocked@domain.com I have plenty of account credits with Apollo, just not sure why or how to get Clay to return the email.