Non-arrival of box notification emails

From February 16, 2023, you will no longer receive any box notification emails that you used to receive as usual.
I tried to check if there was any change in the reception settings of the department that manages the mailer or firewall on this side around the relevant period, but there was no such history, and on the contrary, a transmission error occurred on the Box side. We have received a report suggesting this, which is attached below.
Thank you for your support.
 
When I checked the server log based on the contents of the notification email, it was found that an email thought to be the relevant notification was sent to our MX server around 11:21 on February 16, as you pointed out, but it was successfully delivered. There was a log that returned a response to the source server [149.72.116.240] to wait for a while and then resend. After that, the log sent to <my email address> could not be confirmed. Depending on the delivery system, there was also a system that did not resend if delivery could not be made, and retained information that delivery was not possible, and did not deliver to that address for a certain period of time. We apologize for the possibility, but if the administrator of the system you are using has the above function, could you please adjust it so that a notification email is sent? If so, please contact us to check the delivery log on the server to see if the notification email has connected to our MX server and the delivery has been completed.