Field Notice: FN74342 - Cisco Unified Communications Manager: SMTP May Fail to Connect After March 1, 2026 - Workaround Provided

Available Languages

Updated:December 12, 2025
Document ID:FN74342

Bias-Free Language

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.

High
Impact Rating:
High
First Published:
2025-Dec-15
Last Published:
2025-Dec-12
Revision:
1.1

Notice

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.

Products Affected


Affected Software Product Affected Release Affected Release Number Comments
Unity Connection -   All releases are affected.
Prime Collaboration Deployment -   All releases are affected.
Unified Communications Manager -   All releases are affected.

Defect Information


Defect IDHeadline
CSCwr98478CUCM may fail to connect to Microsoft 365 SMTP server after March 1, 2026
CSCws04982PCD may fail to connect to Microsoft 365 SMTP server after March 1, 2026
CSCws07112CUC may fail to connect to Microsoft 365 SMTP server after March 1, 2026

Problem Description


Cisco Unified Communications Manager (Unified CM), Cisco Prime Collaboration Deployment, and Cisco Unity Connection may fail to connect to the Microsoft 365 SMTP server after March 1, 2026.


Background


After March 1, 2026, Microsoft will remove support for Basic Authentication with the Client Submission (SMTP AUTH) endpoints. The Microsoft 365 retiral notification of basic authentication on Microsoft 365 is available at the following link:

Exchange Online to retire Basic auth for Client Submission (SMTP AUTH)


Problem Symptom


When SMTP interfaces are configured as a client using Basic Authentication to connect with Microsoft 365, the following may be encountered after March 1, 2026:

  • Failure to send emails from Cisco Collaboration products using SMTP Basic Authentication with Microsoft 365.
  • Authentication errors or connection refusals from Microsoft 365 SMTP servers.
  • Disruption of email notifications, alerts, and workflows dependent on SMTP Basic Authentication.

Workaround/Solution


Workaround

Customers are encouraged to use an intermediate SMTP Relay to communicate with the Microsoft 365 SMTP server.


Revision History


VersionDescriptionSectionDate
1.0Initial Release—2025-DEC-15
1.1Updated the lInk to the Microsoft site and aligned dates to the Microsoft announcement.Problem Description, Background, Problem Symptom, Title2025-DEC-12

For More Information

For further assistance or for more information about this field notice, contact the Cisco Technical Assistance Center (TAC) using one of the following methods:

Receive Email Notification About New Field Notices

To receive email updates about Field Notices (reliability and safety issues), Security Advisories (network security issues), and end-of-life announcements for specific Cisco products, set up a profile in My Notifications.

Was this Document Helpful?

FeedbackFeedback

Contact Cisco

This Document Applies to These Products