Signature Warning

This policy setting controls how Outlook warns users about messages with invalid digital signatures.

If you enable this policy setting, you can choose from three options for controlling how Outlook users are warned about invalid signatures:

- Let user decide if they want to be warned. This option enforces the default configuration.
- Always warn about invalid signatures.
- Never warn about invalid signatures.

If you disable or do not configure this policy setting, if users open e-mail messages that include invalid digital signatures, Outlook displays a warning dialog. Users can decide whether they want to be warned about invalid signatures in the future.

Supported on: At least Windows 7
Signature Warning


  1. Let user decide if they want to be warned
    Registry HiveHKEY_CURRENT_USER
    Registry Pathsoftware\policies\microsoft\office\15.0\outlook\security
    Value Namewarnaboutinvalid
    Value TypeREG_DWORD
    Value0
  2. Always warn about invalid signatures
    Registry HiveHKEY_CURRENT_USER
    Registry Pathsoftware\policies\microsoft\office\15.0\outlook\security
    Value Namewarnaboutinvalid
    Value TypeREG_DWORD
    Value1
  3. Never warn about invalid signatures
    Registry HiveHKEY_CURRENT_USER
    Registry Pathsoftware\policies\microsoft\office\15.0\outlook\security
    Value Namewarnaboutinvalid
    Value TypeREG_DWORD
    Value2


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