The recipient has not received the email.
Track and Trace shows that the email was successfully delivered, but the Recipient Server field is blank.
This occurs due to a known issue affecting cases where both the sender and recipient are ESS customers.
Email Security.cloud
The recipient server IP information is missing in Track and Trace logs because of a known issue when both the sender and recipient are ESS customers.
This is a known issue with no ETA currently available.
You may subscribe to this KB article to receive updates about the fix. See: Subscribe to a Broadcom knowledge article
To investigate further on mails not received by the recipient, please contact Broadcom Technical Support.