emails from Taleo lagging/delayed

Summary

I've been experiencing a significant lag from when emails are generated in Taleo to when they are delivered.

Content

I've been experiencing a significant lag from when emails are generated in Taleo to when they are delivered. I've worked with both our internal IT for our outlook servers and with Oracle on their end, but emails are still taking 1+ hours to reach email boxes. Has anyone else been experiencing this? It seemed to start on June 6th, at least that was when I was first notified by our users. They've tried refreshing the zone, looked at server back ups (were not any), and I had our IT team make sure the sender was added to our Outlook as