Outlook Add‑ins Missing

We are currently investigating reports of missing Microsoft Outlook Add‑ins.
We have opened a high priority support case to notify Microsoft of the issue.
At this time, Microsoft is actively working to determine the root cause. The issue affects certain tenants where Add‑ins fail to install or previously installed Add‑ins unexpectedly disappear. Other tenants remain unaffected.
We will provide further updates as soon as additional information becomes available.

As a workaround you can manually deploy the Outlook Add-ins in your Microsoft 365 Tenant.

Total Protection Outlook Add-in Workaround
https://support.hornetsecurity.com/hc/en-us/articles/21797951259537-Manual-installation-of-the-Outlook-add-in

AIRV Outlook Add-in Workaround
https://cp.hornetsecurity.com/manual/en/ai_recipient_validation/t_deploy_ai_recipient_validation_add_in_manually.html

We will provide further updates as soon as additional information becomes available.

We continue to work closely with Microsoft as we investigate the Deploy Issues with our Outlook Add‑ins. Our high‑priority support case remains active, and we are staying in constant communication to support their efforts. At this stage, we unfortunately cannot provide a solution yet, but we highly recommend utilizing the workaround shared below. We will share updates as soon as new information is available through our joint investigation.

Microsoft have deployed a fix for the issue causing Add-ins to disappear. Affected customers will need to reinstall the Total Protection Add-in through the Control Panel.
If the Add-in appears as already installed, please uninstall it first and then reinstall it via the Control Panel.

We will continue to monitor the situation.

The previously communicated fix deployed by Microsoft did not resolve the issue as expected. We have re‑escalated the matter to Microsoft, and remain in close contact with their engineering teams as they reassess the situation.

We understand the impact this may be causing and will share further updates as soon as additional information becomes available.

We are continuing to work with Microsoft through multiple escalation channels regarding the issue affecting Outlook Add-ins. Microsoft’s engineering teams are actively investigating the root cause and working on a resolution. We understand the impact this may have and will provide further updates as soon as additional information becomes available, thank you for your patience thus far.
While we work on resolving the issue, we encourage you to use the recommended workarounds shared below. Be sure to execute each step to successfully deploy the Add‑in manually.

Microsoft is actively preparing a global fix for the Outlook Add‑in issue. We continue to work closely with their engineering teams through multiple escalation channels.
We can confirm that we have successfully tested an early version of Microsoft’s fix. Microsoft is now conducting further quality assurance before beginning a phased worldwide rollout.
We will share additional updates as soon as Microsoft provides a confirmed release timeline. Thank you for your patience.
In the meantime, the recommended workarounds remain available below.

Total Protection Outlook Add-in Workaround
support.hornetsecurity.com/hc/en-us/articles/21797951259537-Manual-installation-of-the-Outlook-add-in

AIRV Outlook Add-in Workaround
cp.hornetsecurity.com/manual/en/ai_recipient_validation/t_deploy_ai_recipient_validation_add_in_manually.html

Microsoft has confirmed that a global fix has been deployed to resolve the issue affecting all existing tenants. Further details can be found in the official documentation:

https://learn.microsoft.com/en-us/office/dev/add-ins/resources/resources-office-add-in-known-issues#issue-intermittent-failure-to-load-or-deploy-office-add-ins-due-to-exchange-authentication-changes

If you previously implemented our temporary workaround, please remove the Add‑in that was deployed via the Integrated Apps section. Once this has been removed, installation through the Control Panel will function normally again.

We will monitor the situation closely.

No further issues have been observed, and we will continue to monitor the situation through the end of the week.
If you encounter any difficulties during the installation of the Outlook add‑in, please make sure to remove any previously applied workaround before installing our Outlook Add-ins via the Control Panel. If you encounter any Issues during the installation please contact our support.

A high number of successful installations have been observed this week, confirming expected behavior across affected environments. We expect this positive trend to continue into the coming week.

If you encounter any technical issues during installation, please contact our Support team. Prior to installing the Add-in via the Control Panel, ensure that any previously implemented workaround has been removed.

A small subset of customers still report the add-in as missing despite successful, error-free installations. As logs confirm successful deployments, affected customers should contact support and provide their Microsoft Tenant ID to help us identify impacted tenants while we continue working with Microsoft on a resolution.

We have also released an updated manifest to fix prior manual installation issues. Customers who experienced problems are advised to retry using the latest version. See our documentation for guidance and the updated manifest: https://support.hornetsecurity.com/hc/en-us/articles/21797951259537-Manual-installation-of-the-Outlook-add-in