Policy

Use UserIssuerSerialNumber

This policy setting determines whether Outlook uses IssuerSerialNumber as the SignerIdentifier, which enables third-party email client software applications to read encrypted Outlook email messages. For more information about Cryptographic Message Syntax, refer to the RFC 5652 specification. If you enable or do not configure this policy setting, Outlook uses the IssuerSerialNumber as the SignerIdentifier. If you disable this policy setting, Outlook uses SubjectKeyIdentifier for the SignerIdentifier, which might prevent third-party email client software applications from reading encrypted Outlook email messages.

Policy
Pack Microsoft Office
Category Microsoft Outlook 2016 / Security / Cryptography
Policy ID 321452db7ed9
Internal name L_SMIMEUseIssuerSerialNumber

Registry

Copy registry mappings

HKCU\software\policies\microsoft\office\16.0\outlook\security\useissuerserialnumber (enabled) = 1
HKCU\software\policies\microsoft\office\16.0\outlook\security\useissuerserialnumber (disabled) = 0

Policy notes

This policy setting determines whether Outlook uses IssuerSerialNumber as the SignerIdentifier, which enables third-party email client software applications to read encrypted Outlook email messages. For more information about Cryptographic Message Syntax, refer to the RFC 5652 specification. If you enable or do not configure this policy setting, Outlook uses the IssuerSerialNumber as the SignerIdentifier. If you disable this policy setting, Outlook uses SubjectKeyIdentifier for the SignerIdentifier, which might prevent third-party email client software applications from reading encrypted Outlook email messages.

Related policies

Always use TNEF formatting in S/MIME messagesCheck for the user's private key when the user sends an encrypted email that includes the user as a recipientDo not check e-mail address against address of certificates being usedDo not display 'Publish to GAL' buttonDo not provide Continue option on Encryption warning dialog boxesEnable Cryptography IconsEnable Retrieval of Remote Certificate Authority Information