In Microsoft Exchange Server 2019 or Exchange Server 2016, EdgeTransport.exe crashes because of a stack overflow exception. You may see this event in the application logs:
Log Name: Application
Source: Application Error
Event ID: 1000
Task Category: (100)
Faulting application name: edgetransport.exe, version: 15.1.1847.3, time stamp: 0x5d5c6650
Faulting module name: clr.dll, version: 4.7.3062.0, time stamp: 0x5ab9567c
Exception code: 0xc00000fd
Fault offset: 0x0000000000004fb4
Faulting process id: 0xfc
Faulting application start time: 0x01d59a7080bdc2fd
Faulting application path: C:\Program Files\Microsoft\Exchange Server\V15\Bin\edgetransport.exe
Faulting module path: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\clr.dll
Report Id: ReportID
Faulting package full name:
Faulting package-relative application ID:
This issue occurs because the error "451 4.7.0 Temporary server error. Please try again later. PRX5" is populated in the smtp.target response variable. It causes the stack for filling the InboundProxyLayer's buffer keeps building up.
To fix this issue, install one of the following updates:
For Exchange Server 2019, install the Cumulative Update 7 for Exchange Server 2019 or a later cumulative update for Exchange Server 2019.
For Exchange Server 2016, install the Cumulative Update 18 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.
Learn about the terminology that Microsoft uses to describe software updates.