Back pressure is a system resource monitoring feature of the Microsoft Exchange Transport service that exists on Microsoft Exchange 2013 Mailbox servers and Edge Transport servers. What this means is that the Exchange server monitors key resources, such as hard drive space and memory, and under pressure, can take action to prevent service unavailability. While this can prevent system resources from being completely exhausted, back pressure can cause service degradation.
The Exchange server tries to process existing messages before accepting any new messages and therefore introduces delivery delays. Exchange Server resource sizing is an exact science. Over time, with more users, higher email volume, and larger message sizes, environment will change over time. Therefore the initial Exchange Server sizing may be inadequate a year later.
In this scenario back pressure was avoided by actively monitoring the Exchange Server resources with Intelligent Monitoring. As shown in the figure below, the Exchange mailbox server memory utilization was increasing. Knowing that this was happening allowed the IT team to completely avoid Exchange performance issues by allocating more memory to the Exchange Server. Identifying this potential issue would not have happened without having Intelligent Monitoring in place. Intelligent Monitoring gives you access to server performance information easily and with the guidance of the PCIS team, can avert a potential Exchange service degradation issue.