MS-220T00: Troubleshoot Microsoft Exchange Online

Course Modules

Module 1: Exchange Online Mail Flow & Security Architecture

Focuses on diagnosing routing mechanics, external mail flow, and Defender for Office 365 protections.

Lesson 1.1: Core Mail Routing & Diagnostic Tools

• Reviewing and interpreting internet message headers.

• Running and interpreting Message Trace results, including associated delivery policies.

• Identifying transport rules, conditional routing, and evaluation order during transit.

• Troubleshooting "silent drops" (users cannot send/receive, but no NDR is generated).

• Diagnosing tenant-to-tenant misrouting issues and delivery delays.

Lesson 1.2: External Systems & Hybrid Mail Flow

• Reading and analyzing SMTP protocol logs for hybrid and third-party systems.

• Troubleshooting DNS-related mail flow issues (MX, SPF, DKIM, DMARC records).

• Diagnosing SMTP relay and TLS/SMTP certificate validation issues.

Lesson 1.3: Non-Delivery Reports & Content Rules

• Identifying types of NDRs and interpreting underlying NDR error codes.

• Determining active rules impacting attachments and blocked attachment file types.

• Analyzing inbox rules triggered upon arrival and fixing corrupted inbox rules.

Lesson 1.4: Microsoft Defender for Office 365

• Determining why an email was marked as spam or phish.

• Investigating message isolation reasons in the Quarantine portal.

• Troubleshooting and fine-tuning spam filter policies.

• Managing false positives and false negatives via submissions and tenant allow/block lists.

Module 2: Compliance, Retention, & Auditing

Focuses on eDiscovery, data retention logic, message protection, and administrative auditing.

Lesson 2.1: eDiscovery, Holds, & Content Deletion

• Identifying RBAC roles required for eDiscovery actions.

• Troubleshooting eDiscovery searches, exports, and in-place/eDiscovery holds.

• Determining the specific types of holds associated with an item.

• Searching for and hard-deleting targeted messages across an organization.

• Clearing, purging, and managing the Recoverable Items folders.

Lesson 2.2: Retention Policies & Messaging Records Management (MRM)

• Describing Microsoft Purview compliance retention policies vs. legacy MRM.

• Understanding retention tag types, actions, and the item retention age calculation process.

• Troubleshooting issues when creating and applying retention policies.

• Reviewing and interpreting MRM mailbox diagnostics logs and item properties.

Lesson 2.3: Message Encryption (OME) & S/MIME

• Troubleshooting issues where messages are not encrypted or decrypted as expected.

• Resolving external vs. internal decryption discrepancies for protected emails.

• Troubleshooting mobile device limitations with Microsoft 365 protected messages (read/reply/forward).

• Configuring and debugging mail flow rules for encryption and handling email revocations.

• Troubleshooting S/MIME certificate and deployment issues.

Lesson 2.4: Mailbox Auditing & Journaling

• Troubleshooting Unified Audit Log search failures.

• Investigating user actions (e.g., tracking missing items or unexpected deletions).

• Tracking bulk administrative or automated actions (creation, moves, modifications).

• Tracking and identifying non-owner access and actions.

• Resolving audit log retention period discrepancies and "auditing not working" states.

• Troubleshooting journaling: duplicate entries, unjournaled mail, and OME decryption issues.

Module 3: Client Connectivity & Authentication

Focuses on Desktop, Web, and Mobile access tracking and credential troubleshooting.

Lesson 3.1: Outlook Desktop Connection & Authentication

• Obtaining and reading Outlook client configuration information (Connection Status / Autodiscover test).

• Troubleshooting Exchange authentication policies and Client Access Rules (CARs).

• Diagnosing Modern Authentication (OAuth) blockages and legacy auth deprecation issues.

• Resolving Outlook desktop connectivity failures and continuous password prompt loops.

Lesson 3.2: Outlook on the Web (OWA) & Autodiscover

• Troubleshooting OWA sign-in errors, browser blocks, and conditional access impacts.

• Diagnosing internal and external Autodiscover routing failures.

Lesson 3.3: Mobile Device Access & ActiveSync

• Identifying mobile device access states and investigating statistics for blocks.

• Managing and reviewing the Allow/Block/Quarantine (ABQ) list.

• Troubleshooting Exchange device access rules.

• Reviewing and interpreting ActiveSync logs to isolate Outlook Sync / EAS connection issues.

• Troubleshooting native OS ActiveSync connectivity profiles.

Module 4: Calendar & Collaboration Troubleshooting

Focuses on scheduling, delegation permissions, and resource management.

Lesson 4.1: Internal Calendaring & Delegation

• Reviewing and analyzing mailbox and calendar diagnostic logs via PowerShell.

• Troubleshooting broken manager/delegate tracking and scheduling permissions.

• Isolating Resource Booking Assistant automated processing and policy failures.

Lesson 4.2: Calendar Sharing & Publishing

• Troubleshooting internal/external calendar sharing permission issues.

• Publishing calendars externally and troubleshooting external access links.

• Determining why content for a published or federated calendar is not up to date.

Module 5: Exchange Online Object & Tenant Configuration

Focuses on directory provisioning, recipient types, organization-wide configurations, and public folders.

Lesson 5.1: Object Provisioning & Recipient Management

• Interpreting and fixing validation errors encountered during Entra ID/Exchange object provisioning.

• Determining when and how to restore or recover an inactive mailbox.

• Managing and troubleshooting resource mailboxes (rooms and equipment).

• Isolating issues purging deleted users or handling orphaned objects.

Lesson 5.2: Advanced Recipient Types

• Troubleshooting automatic email forwarding blocks (outbound anti-spam policy rules).

• Fixing object matching issues between on-premises Active Directory and cloud Azure AD.

• Troubleshooting distribution lists and Dynamic Distribution Group membership evaluation.

• Diagnosing archive mailbox issues, including auto-expanding archive allocation limits.

Lesson 5.3: Org-Wide Settings & Public Folders

• Troubleshooting custom domain setup, verification, and configuration issues.

• Isolating Address Book Policies (ABP) and Address List segregation issues.

• Configuring and troubleshooting allowed file types, Mailbox Plans, and CAS mailbox plans.

• Troubleshooting Exchange Online public folder access (cloud-only, hybrid access, and mail-enabled public folders).

• Resolving public folder email delivery and load-balancing issues.

Module 6: Hybrid Deployments & Cross-Premises Migrations

Focuses on managing co-existence environments and mailbox migration pathways.

Lesson 6.1: Hybrid Configuration & Co-existence

• Troubleshooting Hybrid Configuration Wizard (HCW) execution and log errors.

• Isolating cross-premises hybrid mail flow issues (Centralized Mail Transport vs. Direct).

• Troubleshooting free/busy (free/busy lookup failures) between cloud and on-prem.

• Synchronizing remote recipient attributes (dirsync/Entra Connect attribute mapping) with Exchange Online.

Lesson 6.2: Mailbox Migrations

• Troubleshooting migration endpoint creation and credentials.

• Reviewing migration users, move requests, and parsing move logs.

• Diagnosing slow migrations (throttling, network performance) and failed migrations.

• Interpreting Data Consistency Score (DCS) metrics and managing skipped items.

• Troubleshooting legacy public folder migration issues to Exchange Online.