Mail Flow & TransportConnectors & Partner Mail Flow

Connectors & Partner Mail Flow

25 mins

Understanding the Concept

Connectors in Exchange Online define how mail flows between your organization and external systems. Inbound connectors receive mail from specific sources (partner orgs or on-premises), while outbound connectors send mail to specific destinations.

Partner connectors enforce TLS encryption for specific domains, ensuring secure communication. Organization connectors handle mail flow with on-premises Exchange servers in hybrid configurations.

Certificate-based or IP-based validation ensures that connectors only process mail from authorized sources, preventing spoofing and unauthorized relay.

Key Points

•Inbound connectors: from partner org or on-premises to Exchange Online

•Outbound connectors: from Exchange Online to partner org or on-premises

•TLS enforcement ensures encrypted partner communication

•Certificate or IP-based validation authenticates connector sources

•Hybrid connectors route mail between cloud and on-premises

•Test connector validation using Test-MailFlow cmdlet

Why This Matters

Connectors are essential for hybrid mail flow, partner communications, and integrating third-party email security gateways. Misconfigured connectors can break mail delivery or create security vulnerabilities.

Common Mistakes to Avoid

✗Not enforcing TLS on partner connectors, sending emails unencrypted

✗Misconfiguring hybrid connectors causing mail loops

✗Forgetting to validate connector certificates before deployment

Interview Discussion Points

💡Explain the difference between inbound and outbound connectors

💡Describe how to set up secure mail flow with a partner organization

💡Discuss hybrid connector requirements and configuration

MS-203 Exam Tips

📝Know connector types and when to use each (partner vs organization)

📝Understand how to enforce TLS and certificate validation on connectors

📝Be prepared for hybrid mail flow connector configuration scenarios

Transport Rules & Mail Flow Rules

Accepted Domains & Email Address Policies