Update 08/14/2023 14:47 PM 14 days
The systems impacted by this issue have been removed from the network and we've confirmed that messages that were in the queue have been scanned and delivered.
We have removed the network that caused this issue from active routing. Delivery times are not being impacted.
Details: The error command 5.7.1 was issued due to a permanent failure in the SPF framework that validates senders domains and their SPF DNS records. The issue was caused by an upstream DNS server taking too long to respond to certain requests. This issue (and the related one with admin.exchangedefender.com) were caused by an OTA update to our network switches which caused some systems not to bring up the appopriate network interfaces (leading to decreased performance leading to timeouts leading to failure leading to errors).