When this problem occurs, the following event is logged in the Application log:
Event Type: Error Event Source: MSExchange Common Event Category: General Event ID: 4999 Description: Watson report about to be sent to dw20.exe for process id: <ID>, with parameters: E12, c-RTL-AMD64, <version number>, edgetransport, M.E.M.EdgeAgents, M.E.M.A.StringBlock.ReadStringUnsafe, system.indexoutofrangeexception, be38, <version number>. ErrorReportingEnabled: False