Update has resolved the issue and email is being delivered properly.
Feb 14, 14:15 EST
The core problem has been traced to a particular function, which is blocking additional processing. As usage increases during the day, the queue gets to a point that it cannot maintain "real-time" delivery of these messages. As the usage decreases later in the day, the queue begins to catch up.
Engineering has released a fix for this issue, and it will be rolled out tonight during an emergency maintenance window.
Feb 13, 11:48 EST
Email delivery has been stable. We are continuing to monitor for prompt delivery.
Feb 12, 09:03 EST
Engineering has indicated that they have found the issue and implemented a fix. We will continue to monitor the resolution.
Feb 11, 12:36 EST
Problem appears to still be an issue. Engineering is continuing to troubleshoot the delay.
Feb 11, 08:53 EST
The delay on sending emails appears to be resolved. We will continue to monitor the situation.
Feb 10, 08:49 EST
The issue has been identified and a fix is being implemented.
Feb 7, 17:00 EST
Engineers have isolated the issue and are still working towards a resolution.
Feb 7, 16:37 EST
It appears that there is a delay in delivering new emails. We are working to identify the cause of the delay.
Feb 7, 10:14 EST
We are currently investigating reports of some email notifications not being delivered properly.
Feb 7, 09:57 EST