If emails are not being delivered to all recipients, there are several actions to take.

1. Check the email address format for typos or incorrect domain information.
2. Check for any blocked domains due to SPAM ratings.
3. Increase the SPF records or switch hosting service providers.
4. Analyze the log files to gain further insight on why some emails are not being delivered.
5. Whitelist the email address of certain recipients, specific domains, or even IP address.