Disable Internationalized Domain Names (IDN) in Outlook

Supported on: At least Windows Server 2008 R2 or Windows 7

Registry

HKCU software\policies\microsoft\office\16.0\outlook\options\general

Value name: disableidn

Enabled: disableidn = 1

Disabled: disableidn = 0

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.