Exchange Mailbox: Use a User Mailbox Instead of a Shared Mailbox

Summary

For optimal security, reliability, and manageability, we recommend using a designated user mailbox rather than a shared mailbox when configuring Exchange Online for email integration.

While a shared mailbox can technically be used, it introduces additional complexity and potential authentication issues. A dedicated user mailbox provides clearer ownership, simpler authentication, and better long‑term maintainability.

Recommended Approach: Dedicated User Mailbox

We recommend creating and using a designated user account with an Exchange Online mailbox for sending and managing emails.

Benefits of a User Mailbox

• Improved security – Direct authentication using a single, controlled account

• Simpler configuration – No dependency on delegated access for authentication

• Better auditing – Clear ownership of sent messages and sign‑ins

• More predictable behavior – Avoids limitations around shared mailbox authentication

Licensing Requirements

• The user account only requires an Exchange Online license

• No additional Microsoft 365 services are required

• The user account does not need any permissions on the SharePoint site

Using a Shared Mailbox (Not Recommended)

It is technically possible to send email from a shared mailbox, but there are important limitations to be aware of.

Important Considerations

• Shared mailboxes cannot authenticate on their own

• Authentication must be performed using a user account

• That user account must have either:

  • Full Access, or

  • Send As / Send on Behalf permissions for the shared mailbox

• This adds administrative overhead and increases the risk of misconfiguration

⚠️ Note: Even when using a shared mailbox, the authenticating user account still requires an Exchange Online license.

Because of these challenges, shared mailboxes should only be used in exceptional scenarios where a dedicated user mailbox is not possible.

Configuration Guide

Step‑by‑step instructions for configuring email settings are available here:

🔗 Configure Email Settings in SharePoint|sapiens
https://www.sharepointsapiens.com/help/documentation/configure-email-settings-in-sharepoint/

Best Practice Recommendation

✅ Always prefer a dedicated user mailbox for email integration
⚠️ Use shared mailboxes only if there is a clear, justified requirement
🔐 Keep the user account restricted to Exchange Online only, where possible