Field Notice: FN74358 - Cisco Expressway: SMTP May Fail to Connect After March 1, 2026 - Workaround Provided

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Updated:December 19, 2025
Document ID:FN74358

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High
Impact Rating:
High
First Published:
2025-Dec-19
Last Published:
2025-Dec-19
Revision:
1.0
Cisco Bug IDs:

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
Expressway Core and Edge X14 X14.0.0, X14.0.1, X14.0.10, X14.0.11, X14.0.2, X14.0.3, X14.0.4, X14.0.5, X14.0.6, X14.0.7, X14.0.8, X14.0.9, X14.2.0, X14.2.1, X14.2.2, X14.2.5, X14.2.6, X14.2.7, X14.3.0, X14.3.1, X14.3.2, X14.3.3, X14.3.4, X14.3.5, X14.3.6, X14.3.7 All releases are affected
Expressway Core and Edge X15 X15.0.0, X15.0.1, X15.0.2, X15.0.3, X15.2.0, X15.2.1, X15.2.2, X15.2.3, X15.2.4, X15.2.4., X15.3.0, X15.3.1 All releases are affected

Defect Information


Defect IDHeadline
CSCws03948Expressway may fail to connect to Microsoft 365 SMTP server after March 1, 2026

Problem Description


Cisco Expressway may fail to connect to the Microsoft 365 SMTP server after March 1, 2026.


Background


After March 1, 2026, Microsoft will no longer support Basic authentication with Client Submission (SMTP AUTH) endpoints. The notification about the retirement of Basic authentication on Microsoft 365 is available at the following link: https://techcommunity.microsoft.com/blog/exchange/exchange-online-to-retire-basic-auth-for-client-submission-smtp-auth/4114750


Problem Symptom


After March 1, 2026, Cisco Expressway SMTP interfaces that are configured as clients using Basic authentication to connect with Microsoft 365 may encounter the following issues:

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

Workaround/Solution


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-19

For More Information

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