
As you may know, Powershell can access the Registry directly, just as it can access the file system. There are two predefined psdrives available when you load Powershell that point to the Registry hives HKEY_LOCAL_MACHINE (HKLM) and HKEY_CURRENT_USER (HKCU). You can add others if you choose by configuring your Powershell user or machine profile.
To use Powershell to add (or change) an entry in the registry to increase the OWA session timeout for "trusted" clients to 8 hours (480 minutes), use the Exchange Management Shell and type the following command or use Regedit: (the usual warnings apply)
New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Services\MSExchange OWA' -Name TrustedClientTimeout -Value 480 -Type dword
Restart IIS from a command prompt using iisreset /noforce and your users will love you.
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