Home > Glossary > Microsoft 365 Administrator > Shared Mailboxes

📖 What is Shared Mailboxes?

Shared Mailboxes are specialized mailboxes used by multiple users to monitor and send email from a common address, such as [email protected]. They do not require a separate license if they remain under 50GB and have delegated access.

🥋 Sensei Says:

"Watch for the license requirement. If a shared mailbox exceeds 50GB, you must assign an Exchange Online Plan 2 license to it."

📚 Certification: Microsoft 365 Administrator (MS-102)

🔑 What are the Key Concepts of Shared Mailboxes?

  • Delegated permissions include 'Full Access' for managing the mailbox and 'Send As' or 'Send on Behalf' for sending emails from the shared address.
  • Shared mailboxes are free and do not require a license as long as the total storage remains under 50 GB.
  • Users accessing a shared mailbox must possess their own licensed Microsoft 365 account; the shared mailbox does not provide licensing to users.
  • Automapping automatically adds the shared mailbox to a user's Outlook desktop client once Full Access permissions are granted via the admin center.
  • To enable an In-Place Archive or increase storage beyond 50GB, an Exchange Online Plan 2 license must be assigned to the shared mailbox.

🎯 How does Shared Mailboxes appear on the MS-102 Exam?

You may be asked to recommend a mailbox type for a department that needs a single email address for multiple staff members to monitor and respond to. You must identify the Shared Mailbox as the solution to avoid unnecessary licensing costs.

A scenario might describe a shared mailbox that has stopped receiving emails because it reached its 50GB capacity. You will need to identify that assigning an Exchange Online Plan 2 license is the required solution to restore mail flow.

Expect questions about the difference between 'Send As' and 'Send on Behalf' permissions, specifically how the 'From' field appears to the external recipient and which permission is more appropriate for professional corporate branding.

❓ Frequently Asked Questions

Does a user need a license to access a shared mailbox?

Yes. While the shared mailbox itself is free under 50GB, any user granted access to it must have their own licensed Microsoft 365 mailbox to authenticate and access the shared data.


What happens if I grant Full Access but the mailbox doesn't appear in Outlook?

This is usually an automapping delay. While automapping is the default behavior, you can manually add the shared mailbox in Outlook account settings or verify that the user has the correct permissions.

Related Terms from Microsoft 365 Administrator

📝 Related Study Guides

Comparison 8 min read

CISSP vs CISM: Which Certification Should You Pursue in 2026?

Choose CISSP if you want broad technical security expertise across eight domains, including cryptography, network security, and software development. Choose CISM if you're focused on information security management, governance, and risk management from a leadership perspective. CISSP is ideal for hands-on security architects, while CISM is designed for security managers and directors.

Career Guide 9 min read

The IT Certification Roadmap: Where to Start in 2026

Start your IT certification journey in 2026 with CompTIA A+ for general IT foundations, then branch into networking (Network+), cybersecurity (Security+), or cloud computing (AWS Cloud Practitioner or Azure Fundamentals) based on your career goals. Each path leads to advanced certifications like CISSP, AWS Solutions Architect, or CISM within 2-3 years of focused progression.

Comparison 10 min read

CISSP vs CISM: Which Certification Should You Pursue in 2026?

The CISSP is a broad, technical-to-managerial certification focusing on security operations and architecture across eight domains. In contrast, CISM is a specialized management certification centered on governance, risk management, and program development. Choose CISSP for comprehensive security expertise and CISM if you are pivoting specifically into security leadership and governance roles.

🧠

Test Your Knowledge

Think you understand Shared Mailboxes? Put it to the test with our practice exam.

Try 10 Free Questions

⭐ 1,000 expert-curated questions available with Premium

Upgrade Premium