Disable emails from test site

Summary:

In a sandbox environment is there a way to prevent the site from sending emails? I know we can make emails addresses incvalid so they are not recieved, but can we just stop the site from sending them all together?

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Version (include the version you are using, if applicable):

Version: 25D Patch 11

Code Snippet (add any code snippets that support your topic, if applicable):