Cisco Secure Email Cloud Gateway - AsyncOS Announcement 16.0.3 MR

When: Starting Sep 22, 2025

Maintenance Windows: Sunday-Friday
Europe Window: 6 PM to 2 AM (GMT+1)
Canada Window: 6 PM to 2 AM (GMT-7)
Americas Window: 6 PM to 2 AM (GMT-7)
APJ Window: 6 PM to 2 AM (GMT+9)

What: 16.0.3 ESA and SMA – Maintenance Release Upgrade cycle happens in two phases as below:
• Phase 1: SMA AsyncOS upgrade
• Phase 2: ESA AsyncOS upgrade

Your CES instance will be upgraded to the latest AsyncOS 16.0.3 versions.
SMA – 16.0.3-016
ESA – 16.0.3-044

• Phase 1: SMA AsyncOS upgrade release notes are located here
• Phase 2: ESA AsyncOS upgrade release notes are located here

Premium Software Support Customers: Your Cisco CSS (Customer Success Specialist - formerly known as Designated Service Manager) will engage with you directly to evaluate and coordinate these upgrades.

Expected Impact: There should not be any email delivery disruption, however administrative access to your devices during this period may be affected. Customers are requested to validate health of systems post their upgrade window and report to Cisco TAC, if any anomalies are observed.

Secure Email Documentation
Release Notes: https://www.cisco.com/c/en/us/support/security/email-security-appliance/products-release-notes-list.html
User Guide: https://www.cisco.com/c/en/us/support/security/email-security-appliance/products-user-guide-list.html
Command Reference Guide: https://www.cisco.com/c/en/us/support/security/email-security-appliance/products-command-reference-list.html
AsyncOS 16.0 API for Cisco Secure Email Gateway - Getting Started Guide:
https://www.cisco.com/c/en/us/support/security/email-security-appliance/products-programming-reference-guides-list.html
Compatibility Matrix Guide: https://www.cisco.com/c/en/us/support/security/content-security-management-appliance/products-release-notes-list.html
Secure Email Cloud Documentation:
Combined Release Notes: https://www.cisco.com/c/en/us/support/security/cloud-email-security/products-release-notes-list.html
Email Cloud User Guide: https://www.cisco.com/c/en/us/support/security/cloud-email-security/products-user-guide-list.html

CES Status Page: https://status.ces.cisco.com/

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If you have any urgent questions about this maintenance or the possible impact, please contact Cisco TAC: http://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html