Key Takeaways (TL;DR)
- What's happening? Microsoft is retiring Exchange Web Services (EWS) in October 2026, which will permanently break Lightning Sync — every Salesforce org still using it must migrate to Einstein Activity Capture (EAC)
- Hard deadline: October 2026 (EWS disabled globally), but Salesforce recommends completing migration by August 2026 to allow testing time
- Two required steps: (1) Migrate from Lightning Sync to EAC using the built-in Migration Assistant, (2) Upgrade from EWS to Microsoft Graph API
- What you gain: Automatic email logging, AI-powered insights, Agentforce integration, modern OAuth 2.0 security, and Activity 360 reporting
- What you lose if you don't act: All email and calendar sync between Microsoft and Salesforce — permanently
- Timeline: 4–8 weeks for a well-planned migration; 15–30 minutes for small orgs using the Migration Assistant
- Bottom Line: This isn't optional. Lightning Sync will stop working entirely after October 2026. Start your migration today.
Introduction: The Clock Is Ticking
On May 5, 2026, Salesforce sent a product notification that many administrators had been dreading — and many more hadn't seen coming: "ATTENTION: Migrate from Lightning Sync to Einstein Activity Capture."
The message was direct: Microsoft is retiring Exchange Web Services (EWS) in October 2026. Lightning Sync depends on EWS to connect Salesforce with Microsoft 365. When EWS goes dark, Lightning Sync goes with it. No workaround. No extension. No exception.
If your Salesforce org still uses Lightning Sync for email and calendar synchronization, you have approximately five months to complete a two-step migration to Einstein Activity Capture (EAC) and Microsoft Graph API. Miss the deadline, and your teams will wake up one morning to find that every automated email log, every calendar sync, and every contact update between Salesforce and Microsoft has simply... stopped.
This guide provides everything you need to execute a successful migration — from understanding the technical differences between Lightning Sync and EAC, to a week-by-week project plan, to the common pitfalls that trip up even experienced Salesforce admins. We also cover what EAC gives you that Lightning Sync never could, including AI-powered activity insights, Agentforce integration, and modern security architecture.
Related reading: If you haven't already addressed the May 2026 EAC configuration requirement, read our companion guide: Einstein Activity Capture Configuration Changes: What Salesforce Admins Must Do Before May 2026. That post covers the configuration assignment deadline; this post covers the full Lightning Sync migration.
Why Lightning Sync Is Being Retired
The Short Version
Lightning Sync was deprecated in Winter '21 (late 2020). Salesforce stopped making it available to new orgs and announced Einstein Activity Capture as the future of email and calendar sync. For five years, the migration was strongly recommended but not enforced.
Now it's enforced — not by Salesforce, but by Microsoft.
The Microsoft EWS Timeline
| Date | Event |
|---|---|
| July 2018 | Microsoft announces EWS will receive no new features |
| 2023 | Microsoft sets the EWS disablement date for October 2026 |
| January 2024 | The Midnight Blizzard security incident (involving EWS) accelerates deprecation urgency |
| 2025 | Microsoft releases EWS Usage Reports, Analyzer tools, and AI-assisted migration tutorials |
| October 2026 | EWS begins phased global disablement for all organizations |
| April 2027 | EWS is fully disabled — no exceptions |
The Midnight Blizzard incident in January 2024 was a nation-state cyberattack that exploited EWS, dramatically elevating the security case for deprecation. Microsoft has since widened the scope of EWS removal to include all Microsoft applications — Outlook, Office, Teams, and Dynamics 365.
Source: Microsoft — Deprecation of Exchange Web Services in Exchange Online
What Happens If You Don't Migrate
After October 2026, organizations still using Lightning Sync will experience:
- ❌ Complete loss of email and calendar sync between Microsoft 365 and Salesforce
- ❌ No new contacts, events, or email data flowing into Salesforce automatically
- ❌ Historical data remains in Salesforce, but no new sync occurs
- ❌ Manual activity logging required — reps must hand-enter every email and meeting
- ❌ Significant productivity loss — estimated 4.5+ hours per rep per week in manual data entry
- ❌ AI and reporting blind spots — Agentforce, Einstein Insights, and activity reports lose their data pipeline
Lightning Sync vs. Einstein Activity Capture: Complete Comparison
Understanding the differences between Lightning Sync and EAC is essential for planning your migration. This isn't a simple swap — the two platforms have fundamentally different architectures, capabilities, and limitations.
Feature-by-Feature Comparison
| Dimension | Lightning Sync | Einstein Activity Capture |
|---|---|---|
| Data Storage | Stored directly in Salesforce core database | Stored in Salesforce cloud infrastructure (AWS) outside core database |
| Data Retention | Permanent (follows standard Salesforce retention) | 24 months for standard licenses; configurable with add-ons |
| Email Capture | Contacts and events only — no email content | Automatic email capture (incoming and outgoing) with content |
| Reporting | Fully reportable in standard Salesforce reports | Activity Timeline and dashboards; native reports available with "Sync Email as Salesforce Activity" |
| Setup Complexity | Complex admin configuration with field mappings | Simplified, guided setup with Migration Assistant |
| Customization | Highly customizable field mappings | Limited customization; configuration-based approach |
| Workflow/Flow Triggers | Triggers standard Salesforce automation | No direct workflow triggers unless "Sync Email as Salesforce Activity" is enabled |
| UI Requirements | Lightning Experience and Salesforce Classic | Lightning Experience only; requires Activity Timeline |
| Authentication | Basic authentication via EWS | Modern OAuth 2.0 via Microsoft Graph API |
| Licensing | Included with Sales Cloud and Service Cloud | 100 licenses included; additional licenses required beyond 100 users |
| AI Integration | None | Powers Einstein Email Insights, Opportunity Insights, Lead Scoring, and Agentforce |
| Mobile Support | Limited | Full mobile support |
| Recurring Events | Supported | Not supported (manual entry required) |
| Platform Encryption | Supported (Shield Platform Encryption) | Not supported for EAC data |
| Microsoft API | Exchange Web Services (EWS) — deprecated October 2026 | Microsoft Graph API — Microsoft's modern, supported standard |
| Future Development | None — deprecated since Winter '21 | Active development; new features every release |
Official comparison: Salesforce Help — EAC vs Lightning Sync
What EAC Gives You That Lightning Sync Doesn't
The migration to EAC isn't just about maintaining existing functionality — it's an upgrade. Here's what you gain:
- Automatic Email Logging — EAC captures email content for Accounts, Contacts, Leads, Opportunities, and Quotes. Lightning Sync only synced contacts and calendar events.
- Einstein Email Insights — AI-powered insights surface directly in the Activity Timeline, identifying buying signals, competitive mentions, follow-up commitments, and sentiment changes.
- Relationship Insights — EAC data feeds Relationship Intelligence, showing engagement frequency, recency, and depth across your entire organization.
- Opportunity Insights — AI analyzes email and meeting patterns to predict deal outcomes and surface at-risk opportunities.
- Agentforce Integration — EAC provides the foundational activity data that Agentforce AI agents need for lead scoring, nurturing, autonomous monitoring, and next-best-action recommendations.
- Activity 360 Reporting — EAC data unifies with calls, tasks, and other activities to provide complete engagement reporting.
- Flow-Based Record Matching — With "Sync Email as Salesforce Activity" enabled, captured emails become native Activities accessible to Flows, Reports, APIs, and Agentforce.
- Modern Security Architecture — OAuth 2.0 via Microsoft Graph replaces legacy EWS basic authentication, significantly improving your security posture.
Microsoft Graph API vs. Exchange Web Services (EWS)
| Aspect | EWS (Legacy) | Microsoft Graph API (Modern) |
|---|---|---|
| Authentication | Basic/NTLM authentication | OAuth 2.0 with modern consent flows |
| Security | Vulnerable (Midnight Blizzard exploit) | Hardened with conditional access policies |
| Performance | Slower, aggressive throttling | Faster, intelligent throttling |
| Feature Scope | Mail, calendar, contacts | Mail, calendar, contacts + Teams, OneDrive, SharePoint, and 50+ services |
| Mobile Support | Limited | Full cross-platform support |
| Future Support | Deprecated October 2026; fully disabled April 2027 | Microsoft's strategic investment for all cloud services |
| API Updates | Frozen since 2018 | Continuous development with new capabilities each quarter |
Key resource: Microsoft — EWS to Graph API Mappings
The Two-Step Migration Process
Salesforce and Microsoft require you to complete two distinct steps before October 2026. Missing either one will result in broken sync functionality.
Step 1: Migrate from Lightning Sync to Einstein Activity Capture
Pre-Migration Checklist
- ☐ Verify Lightning Experience — EAC requires Lightning Experience. Migrate Classic users first.
- ☐ Audit current Lightning Sync configuration — Document users, sync directions, field mappings, custom configurations.
- ☐ Check EAC license availability — 100 included with Sales/Service Cloud. Purchase additional if needed.
- ☐ Review reports and dashboards — Identify reports using Lightning Sync data for rebuilding.
- ☐ Document workflow automations — Re-evaluate Process Builder/Flow automations triggered by Lightning Sync.
- ☐ Test in sandbox — Enable EAC in sandbox first.
- ☐ Export historical data — Extract data older than 24 months before migration.
- ☐ Plan user communication — Draft change communications for end users.
Running the Migration Assistant
- Navigate to Setup — Click the gear icon → Setup
- Open Lightning Sync settings — In Quick Find, type "Lightning Sync" and select it
- Launch the Migration Assistant — Click the migration tool banner
- Review migration summary — The assistant shows which settings transfer and flags incompatibilities
- Configure EAC settings:
- ✅ Sync contacts AND events (recommended)
- ✅ Configure email capture direction
- ✅ Set excluded addresses
- ✅ Configure privacy and sharing settings
- Assign users — Add users to EAC configuration by name or profile
- Activate the configuration — Save and activate
- Turn off Lightning Sync — Disable after confirming EAC works
Important: You cannot run EAC and Lightning Sync simultaneously for the same users. Plan your migration in phases — start with a pilot group, validate, then migrate remaining users.
Official guide: Salesforce Help — Move from Lightning Sync to Einstein Activity Capture
Post-Migration Validation
- ☐ Activity Timeline displays expected emails and events
- ☐ Test emails appear on correct Salesforce records
- ☐ Calendar events sync within expected timeframe (5–15 minutes)
- ☐ Excluded addresses are properly filtered
- ☐ Privacy settings working as configured
- ☐ Users can connect Microsoft accounts via EAC Settings
Step 2: Upgrade from EWS to Microsoft Graph API
- Navigate to Setup → Einstein Activity Capture → Settings
- Find the upgrade tool — Look for the Microsoft Graph upgrade notification
- Run the upgrade — Single-click tool to upgrade from EWS to Graph
- Verify OAuth connections — Confirm accounts connected via OAuth 2.0
- Test sync functionality — Verify email and calendar sync continues
Official guide: Salesforce Help — Upgrade to Microsoft Graph in EAC
Note: Microsoft Graph requires your Microsoft 365 admin to approve the Salesforce app registration. Coordinate with your IT team early.
8-Week Migration Project Plan
Week 1–2: Discovery and Planning
- Audit current Lightning Sync configuration
- Inventory reports, dashboards, and automations
- Check EAC license count and purchase if needed
- Identify stakeholders and create communication plan
- Schedule sandbox testing
- Coordinate with Microsoft 365 admin for Graph API permissions
Week 3–4: Sandbox Testing
- Enable EAC in sandbox
- Run Migration Assistant in sandbox
- Configure settings (sync direction, excluded addresses, privacy)
- Test email, calendar, and contact sync
- Validate Activity Timeline
- Test Microsoft Graph API upgrade
- Document issues and gaps
Week 5: Pilot Migration (Production)
- Select 10–25 pilot users
- Run Migration Assistant for pilot in production
- Upgrade pilot to Microsoft Graph
- Monitor for 3–5 business days
- Collect feedback and address issues
Week 6: Full Migration (Production)
- Migrate remaining users
- Assign all to EAC configurations
- Upgrade all connections to Graph API
- Disable Lightning Sync for migrated users
Week 7: Validation and Reporting
- Audit all users for active EAC sync
- Rebuild reports and dashboards
- Update Flows and automations
- Enable "Sync Email as Salesforce Activity" if desired
- Verify Agentforce data pipeline
Week 8: Communication and Closure
- Send org-wide completion communication
- Distribute updated training materials
- Document final configuration
- Fully disable all Lightning Sync configurations
- Schedule 30-day post-migration review
Common Migration Pitfalls and How to Avoid Them
1. The 24-Month Data Retention Surprise
The pitfall: EAC standard licenses retain activity data for only 24 months.
The solution: Export Lightning Sync data before migration using Data Loader or Reports. Store exports in a data warehouse, or use Enhanced EAC licenses for extended retention.
2. Broken Reports and Dashboards
The pitfall: Lightning Sync data is fully reportable; EAC data historically was not.
The solution: Enable "Sync Email as Salesforce Activity" (Summer '25+) for standard report access. Use Activity Timeline dashboards and Einstein Activity Metrics as alternatives.
3. Permission Set Confusion
The pitfall: Users need both an EAC Permission Set License AND assignment to an active configuration.
The solution: Use the Summary tab in EAC Settings to audit permission sets and configuration assignments simultaneously.
4. OAuth Configuration with Microsoft 365
The pitfall: Graph requires OAuth 2.0 app registration in Azure AD. Without M365 admin cooperation, the upgrade stalls.
The solution: Engage your Microsoft 365 admin in Week 1. Provide Salesforce's documentation on required permissions.
5. Recurring Events Don't Sync
The pitfall: EAC does not support recurring event synchronization.
The solution: Communicate this limitation. Recurring events must be managed exclusively in Outlook/Google Calendar or created individually in Salesforce.
6. Workflow and Automation Gaps
The pitfall: Lightning Sync triggers Salesforce automations; EAC does not by default.
The solution: Enable "Sync Email as Salesforce Activity" or redesign automations for Activity Timeline events or Platform Events.
7. The Internal Email Blind Spot
The pitfall: EAC does not capture internal domain emails.
The solution: Document this limitation. Evaluate third-party tools if internal email tracking is critical.
8. User Training and Change Management
The pitfall: EAC uses Activity Timeline, not Related Lists. Users need retraining.
The solution: Update page layouts. Create training materials. Include in Week 8 communications.
EAC License Requirements
| Edition/Add-On | EAC Included | Notes |
|---|---|---|
| Sales Cloud Starter | ✅ Standard (up to 100 users) | Basic email, calendar, and contact sync |
| Sales Cloud Professional | ✅ Standard (up to 100 users) | Basic sync with configuration options |
| Sales Cloud Enterprise | ✅ Standard (up to 100 users) | Full configuration and admin controls |
| Sales Cloud Unlimited | ✅ Included | Higher license limits |
| Einstein 1 Sales Edition | ✅ Included | Full EAC plus Einstein AI features |
| Einstein for Sales (Add-On) | ✅ Enhanced EAC | Extended retention, additional features |
| Sales Engagement (Add-On) | ✅ Included | Advanced activity tracking and sequences |
| Revenue Intelligence (Add-On) | ✅ Included | Pipeline and forecasting insights |
Data Privacy and Security Controls
Privacy Settings in EAC
- Sharing Rules — Configure who can see captured activity data
- Header-Only Capture — Capture metadata without email body content
- Excluded Addresses — Block specific addresses or domains from capture
- Excluded Users — Prevent specific users' activities from being captured
How EAC Data Feeds AI
- Einstein Email Insights — Analyzes email content for sentiment and engagement patterns
- Lead Scoring — Factors email and calendar interactions into dynamic scores
- Opportunity Insights — Uses meeting frequency and email patterns for deal predictions
- Agentforce — AI agents access EAC data for autonomous lead nurturing and deal monitoring
Important: Review how EAC data is stored, retained (24 months standard), and which AI features access it. Configure privacy settings appropriately before enabling EAC.
Best Practices for a Smooth Migration
- Start now — don't wait until August. Starting early gives you time for testing, training, and troubleshooting.
- Test in sandbox first. Always enable EAC and run the Migration Assistant in sandbox before production.
- Phase your rollout. Pilot group first, collect feedback, fix issues, then full organization.
- Engage your Microsoft 365 admin early. Graph API requires Azure AD app registration — don't discover this late.
- Export historical data before migration. Extract data older than 24 months before the switch.
- Enable "Sync Email as Salesforce Activity." This closes the biggest reporting gap between Lightning Sync and EAC.
- Assign users by profile, not individually. Scales better and auto-includes new hires.
- Update page layouts. Add Activity Timeline prominently. Remove or de-emphasize activity Related Lists.
- Communicate early and often. Let users know what's changing and what they need to do.
- Plan for storage. Native Salesforce Activities count against data storage. Implement retention strategies.
FAQ: Lightning Sync to Einstein Activity Capture Migration
What is the Lightning Sync retirement date?
Lightning Sync will stop working in October 2026 when Microsoft disables Exchange Web Services (EWS) globally. Salesforce deprecated Lightning Sync in Winter '21 (late 2020) and has recommended migrating to Einstein Activity Capture since then. Salesforce recommends completing the migration by August 2026 to allow time for testing.
How do I migrate from Lightning Sync to Einstein Activity Capture?
Go to Setup → Quick Find → "Lightning Sync" and launch the Migration Assistant. The tool walks you through transferring settings to an EAC configuration. After migration, assign users, verify sync functionality, then disable Lightning Sync. You must also upgrade from EWS to Microsoft Graph API.
What is the impact of Microsoft EWS retirement on Salesforce?
Microsoft's EWS retirement directly breaks Lightning Sync. After October 2026, no Lightning Sync operations will function. Einstein Activity Capture uses Microsoft Graph API instead, making it immune to the retirement. Complete both the EAC migration and Graph API upgrade.
Does Einstein Activity Capture cost extra?
EAC Standard is included with Sales Cloud and Service Cloud for up to 100 users. Organizations with more than 100 users need additional licenses through add-ons like Einstein for Sales, Sales Engagement, or Revenue Intelligence.
What data will I lose when migrating from Lightning Sync to EAC?
Existing Lightning Sync data (Tasks, Events) remains in Salesforce. However, EAC stores new data with a 24-month retention window for standard licenses. Custom reports may need rebuilding. Workflow automations may not fire unless you enable "Sync Email as Salesforce Activity."
Can I run Lightning Sync and EAC at the same time?
No — not for the same users. A phased approach is recommended: migrate a pilot group first, validate, then migrate remaining users. Different user groups can be on different platforms during the transition.
What are the main limitations of EAC compared to Lightning Sync?
Key limitations: 24-month data retention, recurring events don't sync, limited customization, internal emails aren't captured, Shield Platform Encryption not supported, and Lightning Experience is required. Many gaps are narrowing with each Salesforce release.
How does Einstein Activity Capture work with Agentforce?
EAC provides foundational activity data for Agentforce AI agents — including lead scoring, opportunity analysis, conversation intelligence, and autonomous monitoring. Without EAC, Agentforce has limited visibility into real customer interactions.
Conclusion: Don't Wait — Migrate Now
The Lightning Sync retirement isn't a distant concern — it's happening in approximately five months. Microsoft's EWS deprecation in October 2026 is a hard deadline with no workaround. Every Salesforce organization still running Lightning Sync needs to complete a two-step migration: (1) move to Einstein Activity Capture and (2) upgrade to Microsoft Graph API.
The good news is that this migration is also an upgrade. EAC gives you capabilities Lightning Sync never offered — automatic email logging, AI-powered insights, Agentforce integration, modern security, and a platform that's actively being developed for the future.
Start today. Test in sandbox this week. Plan your pilot for the coming weeks. Complete the full migration by August 2026. Your teams — and your data — will thank you.
Need expert help with your Lightning Sync migration? Vantage Point specializes in Salesforce platform migrations, Einstein Activity Capture configuration, and Agentforce readiness. We've helped hundreds of organizations navigate complex Salesforce transitions — from initial planning through post-migration validation.
👉 Contact Vantage Point to schedule a free migration assessment and get a customized project plan for your organization.
Essential Resources
Salesforce Documentation
- Move from Lightning Sync to Einstein Activity Capture — Official migration guide
- Considerations for Migrating to Einstein Activity Capture — Migration planning checklist
- Why Move from Lightning Sync to EAC? — Benefits overview
- Upgrade to Microsoft Graph in EAC — Graph API upgrade guide
- EAC vs Lightning Sync Feature Comparison
- Microsoft EWS Retirement and Salesforce Impact
Microsoft Documentation
- Deprecation of Exchange Web Services in Exchange Online
- EWS to Graph API Mappings
- Exchange Online EWS, Your Time Is Almost Up
Vantage Point Resources
- Einstein Activity Capture Configuration Changes: What Salesforce Admins Must Do Before May 2026 — Companion guide
About Vantage Point
Vantage Point is a certified Salesforce and HubSpot partner specializing in CRM implementation, integration, and AI-powered automation. We help businesses of all sizes navigate platform changes, optimize their technology stack, and drive measurable results through strategic consulting, MuleSoft integration, Data Cloud activation, and Agentforce deployment. From Lightning Sync migrations to full digital transformation, Vantage Point turns complex technology into competitive advantage.
