For Greenhouse Recruiting to execute a stage transition rule, the candidate must have a valid email address and cannot be marked as Do Not Email.
Verify the candidate's email address
To view a candidate's email address, navigate to the candidate's profile and open the tab on the right side of the page.
Verify the candidate is receiving emails from Greenhouse
If a candidate didn't want to receive emails from Greenhouse, your team may have blocked their profile from receiving further communication. Candidates who won't receive emails are blocked with a red tag above their name.
You can turn off this setting by clicking the three dots in the top right corner of their profile and choosing Allow emails to candidate from the list.
Additional resources