Email Alerts and Approval Emails Not Being Sent in Salesforce Sandbox

If workflow rules or approval processes emails are not being received in the Sandbox, make sure that "All email" is selected under your Sandbox's Deliverability.

To confirm or turn on 'All Email' in Sandbox Delivery Settings

Notes: 

• If the Access level is already set to All email you may consider the following article to begin troubleshooting your Workflow Rule Criteria: Set the Criteria for Your Workflow Rule.
• If the workflow is configured properly and the sandbox access level is set appropriately, it may be a deliverability issue. See Testing Deliverability for additional troubleshooting steps.
• This may be a result of an update to Stop Automated Field updates from Suppressing Email Notifications.