Services
Summary
New Microsoft Outlook for Windows desktop will support an admin setting to define S/MIME signature inheritance in replies, rolling out from late July to late August 2025. The setting, NoSignOnReply, can be configured to inherit or not inherit S/MIME signatures. This change does not apply to Outlook for Web. No admin action is required before rollout.
Details
Updated July 22, 2025: We have updated the timeline. Thank you for your patience.
New Microsoft Outlook for Windows desktop will soon support an admin setting to define the application of S/MIME signatures in "reply to" scenarios. This setting enables admins to define if an S/MIME signature will be inherited by default in Reply and Reply all scenarios.
When this will happen:
For new Outlook for Windows desktop:
- General Availability (Worldwide): we will begin rolling out late July (previously early July) and expect to complete by early August 2025 (previously mid-July).
- General Availability (GCC): We will begin rolling out early August 2025 (previously mid-July) and expect to complete by late August 2025 (previously early August).
For Outlook for Web:
After further review we have decided not to proceed with this change at this time for Outlook for Web. We apologize for any inconvenience.
How this will affect your organization:
After this rollout, you can use the new setting called NoSignOnReply to define Signing on Reply and Reply all. Using this setting, admins can define inheritance of S/MIME signature for its users. The NoSignOnReply setting is available in Microsoft Entra ID (formerly Active Directory).
NoSignOnReply = $False. When value = False, Reply and Reply all will inherit the S/MIME signature. Users will need to go to S/MIME settings and remove S/MIME signature.
NoSignOnReply = $TrueThis is the default state. Reply and Reply all will not inherit S/MIME signature. In cases where incoming email has S/MIME encryption and a signature attached, this setting will only inherit encryption and not the signature. This setting can be useful in scenarios where your organization has not configured S/MIME signatures for its users.
As an alternative, admins can configure this setting with the cmdlet Set-SmimeConfig (Set-SmimeConfig (ExchangePowerShell) | Microsoft Learn. Admins can configure this setting in the Microsoft Exchange Management Shell or the Microsoft Exchange Online Shell.
What you need to do to prepare:
This rollout will happen automatically by the specified dates with no admin action required before the rollout. Review your current configuration to assess the impact on your organization. You may want to notify your users or admins about this change and update any relevant documentation.
If your organization does not use S/MIME emails, you do not need to take any action.
If your organization has enabled communications with S/MIME, you may need to review this setting based on your preferences for the behavior.
Learn more about this new setting and other S/MIME settings available for admins to define: Set-SmimeConfig (ExchangePowerShell) | Microsoft Learn
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