I wanted to bring something to your attention about a change I found since the Feb 2025 windows updates.
Today we have had issues with a handful of servers giving errors such as An operation on a socket could not be performed because the system lacked sufficient buffer space
It ends up that windows now screws up when it has outbound TCP connections to ports higher than 5000, on our smartermail Servers we have on port 9998 which is over the 5000 number which caused the server to stop allow ANY kind of outgoing connection or get blocked after a period of time.
Smartertools should maybe add to their next update the reg changes
Here is a powershell script MaxUserPort.ps1 that I created. save/execute this on your server to fix this issue, your server will reboot.
Apply this to any remote windows server that connects to your smartermail on port 9998.
# Set registry path
$RegPath = "HKLM:\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters"
# Set MaxUserPort to allow ephemeral ports up to 65534
Set-ItemProperty -Path $RegPath -Name "MaxUserPort" -Value 65534 -Type DWORD -Force
# Confirm change
Write-Host "MaxUserPort has been set to 65534."
# Prompt for restart
$Restart = Read-Host "Restart required. Do you want to restart now? (Y/N)"
If ($Restart -match "[Yy]") {
Restart-Computer -Force
} Else {
Write-Host "Restart skipped. Please restart manually for changes to take effect."
}