Disable Internationalized Domain Names (IDN) in Outlook
Verified with Microsoft 365/Office 5568.1000 — updated on September 4, 2026
Supported on: At least Windows Server 2008 R2 or Windows 7
Path in the GPO console
User Configuration\Administrative Templates\Microsoft Outlook 2016\Outlook Options\Mail Format\International Options Description
By default, Outlook supports Internationalized Domain Names (IDN) for SMTP addresses in Outlook if Windows provides the appropriate support for this feature. You can disable IDN support so that Punycode rather than native characters are used for rendering SMTP addresses. You might choose to disable IDN support in Outlook if you do not typically expect non-ASCII characters in SMTP addresses. This setting does not affect the support of IDN in URLs.
Registry
HKCU
software\policies\microsoft\office\16.0\outlook\options\general Value name: disableidn
Enabled: disableidn = 1
Disabled: disableidn = 0
Export Builder
BETAConfigure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.
These exports write the registry — this is not a managed GPO. ⓘ
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Disable Internationalized Domain Names (IDN) in Outlook
; State: Enabled
; Supported on: At least Windows Server 2008 R2 or Windows 7
[HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\outlook\options\general]
"disableidn"=dword:00000001More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Disable Internationalized Domain Names (IDN) in Outlook
# State: Enabled
# Supported on: At least Windows Server 2008 R2 or Windows 7
# Warning: In SYSTEM context (the Intune default), HKCU targets the SYSTEM profile. Run this script using the logged-on credentials.
$path = 'HKCU:\software\policies\microsoft\office\16.0\outlook\options\general'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'disableidn' -Value 1 -Type DWordIntune XML
No direct Policy CSP / OMA-URI mapping for this policy. Use the Intune Remediation tab, or ingest the ADMX in Intune.Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Disable Internationalized Domain Names (IDN) in Outlook
# State: Enabled
# Supported on: At least Windows Server 2008 R2 or Windows 7
# Warning: In SYSTEM context (the Intune default), HKCU targets the SYSTEM profile. Run this script using the logged-on credentials.
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKCU:\software\policies\microsoft\office\16.0\outlook\options\general' -Name 'disableidn' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Disable Internationalized Domain Names (IDN) in Outlook
# State: Enabled
# Supported on: At least Windows Server 2008 R2 or Windows 7
# Warning: In SYSTEM context (the Intune default), HKCU targets the SYSTEM profile. Run this script using the logged-on credentials.
$path = 'HKCU:\software\policies\microsoft\office\16.0\outlook\options\general'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'disableidn' -Value 1 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Disable Internationalized Domain Names (IDN) in Outlook
# State: Enabled
# Supported on: At least Windows Server 2008 R2 or Windows 7
# SCCM Configuration Item guidance:
# Create a Configuration Item of type "Setting: Script".
# Discovery script: use the Detection script below.
# Remediation script: use the Remediation script below.
# Compliance rule: the Discovery script output equals 'Compliant'.
# === Detection script ===
# Exported from gporais.com
# Policy: Disable Internationalized Domain Names (IDN) in Outlook
# State: Enabled
# Supported on: At least Windows Server 2008 R2 or Windows 7
# Warning: In SYSTEM context (the Intune default), HKCU targets the SYSTEM profile. Run this script using the logged-on credentials.
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKCU:\software\policies\microsoft\office\16.0\outlook\options\general' -Name 'disableidn' -Expected 1 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Disable Internationalized Domain Names (IDN) in Outlook
# State: Enabled
# Supported on: At least Windows Server 2008 R2 or Windows 7
# Warning: In SYSTEM context (the Intune default), HKCU targets the SYSTEM profile. Run this script using the logged-on credentials.
$path = 'HKCU:\software\policies\microsoft\office\16.0\outlook\options\general'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'disableidn' -Value 1 -Type DWordBuilding a multi-setting collection? Add this setting and generate combined .reg / PowerShell / GPO scripts.