The Microsoft Exchange EdgeSync service on a Hub Transport server may fail to start at server startup, or when you manually attempt to start it.
The Case of the 739,254 NDR Message Loop
The case of an Exchange Server environment experiencing very high message traffic due to an infinite loop of non-delivery reports.
A Guide to Back Pressure in Microsoft Exchange Server
A guide to the back pressure condition that can impact Microsoft Exchange Hub Transport and Edge Transport servers.
PowerShell Script: Check Hub Transport Servers for Back Pressure Events
A PowerShell script to check Hub Transport servers for back pressure event log entries.
The Case of the Hub Transport Server Load Imbalance
An interesting look into a real world problem of multiple Exchange Hub Transport servers not load balancing their traffic load as expected.