Is Exclaimer down?

Exclaimer Engineers are aware of an issue that may cause messages to be delayed when sent to Exclaimer Cloud for Microsoft 365 users in the UK. More information will be provided once it is available.

Exclaimer Engineers have made a change in the UK region to prevent messages from being delivered to the affected servers. This should prevent further messages from being impacted and ensure that impacted messages are processed as expected on the next attempt.

Exclaimer Engineers have confirmed that the error rate is now dropping after a spike in both UK regions, suggesting that other actions taken have been able to address the issue. We are continuing to look into the cause whilst monitoring for any further issues.

After continued monitoring, we have confirmed the issue is no longer occurring. Servers that were displaying errors have been removed and replaced within our UK region to prevent the issue from reoccurring. If you are still seeing issues with mail flow when using Exclaimer at this time, please reach out to our support team directly, who will be happy to help.

Issue: An Azure storage failure in EU2 is resulting in delays processing messages there, engineering teams are actively mitigating the issue. Symptoms: Some messages processed in EU could be delayed. Next Update In: 30 mins or less

Exclaimer Engineers have successfully mitigated the issue and mailflow had returned to normal levels.

The Azure SQL database in EU2 has been fully restored by Microsoft. EU2 endpoints have been re-enabled and mailflow is balanced. All services are confirmed healthy with no further impact to customers.

Engineers are aware of an issue impacting our ability to apply signatures to messages as they are composed, the message 'Failed to acquire auth token' is displayed. There is no impact to email delivery at this time, once the issue has been resolved signatures will start to be applied again. If you have our server-side offering configured, then you will find that signatures are applied to messages after they are sent. If you have any other issues, please contact our support team who will be happy to help

Our team have identified the issue and are actively working on a resolution. Further updates will follow once a fix has been identified.

Engineering has successfully tested and deployed a fix for the add-in to resolve this issue. We will continue to closely monitor the add-in’s performance following the release. Please note that the speed of adoption may vary depending on Outlook cache. If you are currently experiencing any further issues with Exclaimer, please contact our Support team for assistance.

We continue to see a reduction of errors as the new version rolls out and are monitoring its progress. Please note that the speed of adoption may vary depending on Outlook cache. If you are currently experiencing any further issues with Exclaimer, please contact our Support team for assistance.

Microsoft have confirmed that the original issue impacting customers was the result of a server-side change that has since been reverted. Our telemetry also confirms that over 40% of customer requests are coming from the newly released version that similarly resolved customer issues prior to Microsoft's deployment reversal, this continues to roll out. We intend to leave this fix in place as it improves the add-ins resilience to possible authentication issues. If you are currently experiencing any further issues with Exclaimer, please contact our Support team for assistance.

Issue:  Client side signature fails to apply and the message 'Failed to acquire auth token' is displayed. Incident Length: 10 Day\(s\) and 3 hour\(s\)  Incident Date: 18/05/2026, 11:00 UTC - 28/05/2026, 14:05 UTC   Incident Status: Resolved   **Summary**   When composing a new email, the Exclaimer add-in was unable to acquire an authentication token, resulting in signatures not being inserted and an error message being displayed for customers using Outlook for iOS.   All other platforms, including Windows desktop, New Outlook, Mac, Web, and Android, were unaffected.   Server-side signatures continued to apply normally for customers with that configuration.  **Root Cause**   The Exclaimer Outlook Add-in uses a Microsoft authentication flow designed for Office add-ins, which is intended to authenticate users silently in the background without any user interaction. Around 18 May, this silent authentication flow stopped working on Outlook for iOS.   Following an investigation, Microsoft confirmed that a change on their side had caused the silent authentication failure, and that this change was subsequently rolled back.  **Mitigation**   On identifying where the authentication flow was failing, Exclaimer Engineers updated the Outlook Add-in \(v1.29.200\) to introduce a fallback path for when silent authentication cannot complete.   Rather than surfacing an error, the add-in now prompts the user to sign in interactively, allowing authentication to complete and the signature to be applied, improving authentication flow resilience.   This was deployed on 28 May and has been retained permanently as a resilience improvement.    **Incident Timeline**  18/05, ~11:00 UTC - Silent authentication begins failing on Outlook for iOS. Customers start experiencing signature failures on this platform   18/05, 12:51 – Exclaimer releases a new version of the Exclaimer Add-in \(v1.27.200\)   21/05, 19:01 - First report of errors from the Add-in reaches Exclaimer Engineering. Investigation begins.   22/05, 07:26 Engineering confirmed a review of the latest Add-in release had been completed; no active indicators of the issue are present based on the changes made.  10:14 – Active theory was composed on the cause of the issue; code changes are then prepared by Engineering to be released the following week to prevent potential issues over the weekend.     26/05, 10:01 UTC - First code change deployed to improve logging and extend authentication timeouts.    12:10 – Add-in v.1.28.0 is released to the production channel of the Add-in. Review of impacted systems indicates no improvement.   27/05, 13:25 UTC - v.1.29.0 is deployed to both channels to surface more detail from the authentication failure on iOS.    28/05, 07:44 UTC - Severity escalated given customer impact and duration.   10:42 – Issue confirmed to only impact iOS, with other errors likely being unrelated.    11:03 – Internal investigation is prioritized to identify the cause.   11:30 - Internal reproduction of the issue achieved for the first time, enabling rapid iteration on a fix.   13:02 - The point of failure in the authentication flow fully identified, Exclaimer Engineers also identify development of a Fix and begin prioritizing a full release.   13:50 – Add-in version \(v1.29.200\) is prepared for release, awaiting confirmation of the resolution within the preview channel before being released to the production channel.   14:05 - Updated add-in \(v1.29.200\) verified in preview and released out to production channel.   14:31 - Customer confirmation of resolution is received   29/05, 08:10 UTC - Microsoft confirms that a change on their side caused the authentication failure and that it has been rolled back. Exclaimer Engineers agree to keep the changes applied based on this information at this time.

We are investigating a possible service alert. Issue: Users are unable to receive any authentication tokens when attempting to login to https://portal.exclaimer.com using password login. The issue currently looks to only be affecting users who are logging into the Exclaimer portal using Password login. Logins using Microsoft/Google SSO currently get through without any issues. Symptoms: Users will be prompted to enter a token when trying to login to the portal but no authentication tokens are received in the user's registered email address.

We are continuing to investigate the issue to determine the root cause. Our IT will report back shortly

We are still continuing to investigate the issue to determine the root cause. Our IT will report back soon

Our engineers have found the issue and reverted a change. Authentication tokens are now being received and we are continuing to monitor.

We are continuing to monitor for any further issues.

Engineers have confirmed that the previous service alert has been resolved. The service is now back to full health and is working as normal. Thank you for your patience.

Issue: Authentication tokens not received via email for users accessing Exclaimer Portal  Incident Length: 7 hour\(s\) and 17 minutes  Incident Date: 25/05/2026, UTC 03:12– 10:29 UTC  Incident Status: Resolved  **Summary**  Customers logging into the Exclaimer Portal using the Username and Password option were unable to receive authentication tokens for a period of time, preventing them from being able to access the portal.   The exception did not trigger alerting that engaged our key engineering team, resulting in an extended impact time.  **Root Cause**  A process-level exception had occurred and not been successfully restarted. This resulted in token codes being generated but not emailed to users when required.  **Mitigation**  A rollback of the key service that included this process resolved the issue and allowed for a backlog of token code messages that had been generated to be cleared and distributed, which then restored standard service.      Further improvements to internal escalation and alerting processes have been put into place to reduce the delay in acknowledging the issue and beginning resolution steps over public holidays.  **Incident Timeline**  03:12 - Exclaimer Engineers identify a possible issue with customers being unable to log in to the portal when using a Username and Password.    03:36 – Further testing confirms the issue is impacting the authentication code stage, where the email is never received. Other forms of authentication are working as expected.   03:18 – Status page is updated to ensure customers are aware of the issue and to advise alternative login methods.   07:37 – Exclaimer Engineering is alerted and begins to investigate the scope of the issue. Additional engineering resources are called in to investigate the cause.   08:51 – A rollback of the last set of changes made to the service is performed. Testing begins to see if the issue continues   09:04 – Exclaimer Engineers identify the issue is still ongoing despite the rollback work   09:26 - Engineers confirm that the token codes are being generated as expected, indicating the service runs as anticipated to ensure accounts are secure.   09:40 – Consistent replication of the issue is confirmed, expediting testing and remediation processes.   09:59 – Exclaimer Engineers complete further system rollbacks to address the issue.   10:19 – Engineering note that a group of token code messages are confirmed to have been sent as expected and are also received within the mailboxes of accounts.   10:29 – Log review indicates that all submitted codes are processed as expected and new requests for token codes are received by users as expected.

Exclaimer Customers using Exclaimer Cloud for Microsoft 365 would have encountered an error when attempting to run the connector setup wizard from the 'Manage Mail Flow' page, causing the wizard to fail to run. This issue would have no impact on customers who have not previously run the Connector Setup wizard for Microsoft 365