Question: I wrote a program that monitors an IMAP email account. It runs on a schedule, on a laptop that I travel with. Sometimes it runs when my internet connection is through my mobile device, which has a metered connection (that is, I pay by the GB), and I don't want it to, because it uses a lot of bandwidth, and it can wait until bandwidth is free.

So the question is: how can a .NET program determine when the connection its using is metered?

Answer: 
A brief search of MSDN found the NetworkInformation.GetInternetConnectionProfile function. It looks like it's officially part of the Metro interface, but I have heard that desktop applications can access most of the Metro libraries.
In 2021 you can use the powershell .NET framework and a registery KEY like that to test if your ethernet connection is set to metered:

```
$definition = @"
using System;
using System.Runtime.InteropServices;

namespace Win32Api
{

    public class NtDll
    {
        [DllImport("ntdll.dll", EntryPoint="RtlAdjustPrivilege")]
        public static extern int RtlAdjustPrivilege(ulong Privilege, bool Enable, bool CurrentThread, ref bool Enabled);
    }
}
"@

Add-Type -TypeDefinition $definition -PassThru | Out-Null
[Win32Api.NtDll]::RtlAdjustPrivilege(9, $true, $false, [ref]$false) | Out-Null

#Setting ownership to Administrators
$key = [Microsoft.Win32.Registry]::LocalMachine.OpenSubKey("SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\DefaultMediaCost",[Microsoft.Win32.RegistryKeyPermissionCheck]::ReadWriteSubTree,[System.Security.AccessControl.RegistryRights]::takeownership)
$acl = $key.GetAccessControl()
# Use your account "Administrators" or any other which is actually an existing one on your account
$acl.SetOwner([System.Security.Principal.NTAccount]"Administrators")
$key.SetAccessControl($acl)

#Giving Administrators full control to the key
$rule = New-Object System.Security.AccessControl.RegistryAccessRule ([System.Security.Principal.NTAccount]"Administrators","FullControl","Allow")
$acl.SetAccessRule($rule)
$key.SetAccessControl($acl)
$path = "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\DefaultMediaCost"
# you can check for "Ethernet" "Wifi" "4G" etc.
$name = "Ethernet"
#If the Value is 2 = metered
New-ItemProperty -Path $path -Name $name -Value "2" -PropertyType DWORD -Force | Out-Null

```

If you get the following error:

```
Exception calling "SetAccessRule" with "1" argument(s): "Some or all identity references could not be translated.".

```

Try to change the "Administrators" user to any other on your account which exists and has admin rights.