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MC1131777: Outlook for iOS Raises Minimum OS Requirement to iOS 18 and Later

3 minutesPosted inMicrosoft 365 apps, Microsoft 365 suite
MWPRO IMPACT SCORE
OPERATIONAL IMPACT
51
0 25 50 75 100
HIGH IMPACT • REVIEW RECOMMENDED
Recommended Action:
Review the update and plan any required actions before rollout.
▶ What is MWPro Impact Score? Watch our 60‑second explainer

Primary Audience

Microsoft 365 AdminsTeams AdminsTenant AdminsIT ManagersService OwnersEnd Users
Why this score?
AI Confidence
HIGH
Enough detail is available to trust this assessment.
Assessment Reasoning
The change enforces a minimum OS requirement for Outlook for iOS, requiring upgrades to iOS 18 or newer. Admins need to identify users on older devices, communicate the requirement, and manage any support issues. Users on unsupported versions will lose updates and may eventually face sync failures. Although the cutoff began in 2025, ongoing support issues and device replacement planning mean current operational impact remains relevant, but urgency is moderate as the date has already passed.
60
🛡️ Admin Impact
HIGH
55
👥 User Impact
HIGH
35
⚡ Urgency
MEDIUM
50
🔧 Effort
HIGH
ℹ️ WHAT YOU NEED TO KNOW
📌

AT A GLANCE

Outlook for iOS now requires iOS 18 or later. Older OS versions will stop receiving updates and may lose sync over time.
👥

END USERS

Users on iOS 17 or earlier may lose Outlook updates and email/calendar sync.
🛡️

IT ADMINS

Notify users and encourage upgrades to iOS 18 or later to maintain Outlook updates and service.
📅

ROLLOUT TIMELINE

Past:
Late September 2025

📢 Official Microsoft Message Center Announcement

MC1131777: Outlook for iOS Raises Minimum OS Requirement to iOS 18 and Later
Message ID: MC1131777

Updated September 9, 2025: We have updated the timeline. Thank you for your patience.

Introduction

To ensure optimal performance and security, Outlook for iOS will update its minimum supported operating system requirements. Following the release of iOS 26, Outlook for iOS will only support the two most recent versions of iOS, iPadOS, and watchOS. This change aligns with Microsoft’s commitment to supporting the latest Apple platforms.

When this will happen

Rollout will begin in late September 2025 (previously early September) and is expected to complete by late September 2025.

How this affects your organization

Once iOS 26 is generally available:

  • Outlook for iOS will no longer receive updates on devices running iOS 17 or earlier.
  • Users on iOS 17 can continue using the last supported version of Outlook, but over time, the app may stop syncing email and calendar data.
  • iPadOS 17 and watchOS 10 will also be retired. Supported versions will include iPadOS 18 and 26, and watchOS 11 and 26.
  • This change does not affect users running iOS 18 or later.

What you can do to prepare

  • Notify users of the upcoming OS requirement changes.
  • Encourage users to upgrade their devices to iOS 18 or later to continue receiving Outlook updates and ensure uninterrupted service.

Compliance considerations

No compliance considerations identified, review as appropriate for your organization.

Source: Microsoft Message Center • Analysed by MWPro

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