Managing SendOnBehalf Permissions in Exchange Online: A Guide for Distribution Lists and Shared Mailboxes

Welcome to our PowerShell-focused blog! Today’s topic is particularly relevant to Exchange Online administrators. We’re exploring how to manage “Send On Behalf” permissions, a common requirement in organizational email setups. This functionality is crucial for enabling users to send emails on behalf of a Distribution List or a Shared Mailbox. Let’s dive into how to use PowerShell for this purpose, complete with examples and best practices.

Understanding SendOnBehalf Permissions

The “Send On Behalf” permission allows a user to send an email as if they were another user or a group, while still showing the original sender’s name. It’s commonly used in scenarios where assistants need to send emails on behalf of their managers, or teams need to send emails from a shared address.

Setting Up Your Environment

Before starting, make sure you have the Exchange Online Management Module installed, and you’re connected to your Exchange Online session.

Install-Module -Name ExchangeOnlineManagement
Connect-ExchangeOnline

Granting SendOnBehalf Permissions to a Distribution List

1. Identify the Distribution List: Find the email address or alias of the distribution list.
2. Grant Permission: Use the Set-DistributionGroup cmdlet to grant SendOnBehalf permissions.

# Grant SendOnBehalf permission
Set-DistributionGroup -Identity "DistributionList@example.com" -GrantSendOnBehalfTo "user@example.com"

This command grants user@example.com the permission to send emails on behalf of DistributionList@example.com.

Granting SendOnBehalf Permissions to a Shared Mailbox

1. Identify the Shared Mailbox: Find the email address or alias of the shared mailbox.
2. Grant Permission: Use the Set-Mailbox cmdlet to grant SendOnBehalf permissions.

NOTE: This will REPLACE the existing users and/or groups that already have GrantSendOnBehalf permissions.

# Grant SendOnBehalf permission
Set-Mailbox -Identity "SharedMailbox@example.com" -GrantSendOnBehalfTo "user@example.com"

This command grants user@example.com the permission to send emails on behalf of SharedMailbox@example.com. Please note that this will REPLACE the existing users and/or groups that already have GrantSendOnBehalf permissions.

The following command will Add delegates WITHOUT REPLACING existing users and/or groups that are delegates.

Set-Mailbox -Identity "SharedMailbox@example.com" -GrantSendOnBehalfTo @{Add="user1@example.com","user2@example.com"}

NOTE: Ensure there are NO SPACES between ADD, the “=” sign, and values.

Removal is the similar as the above except Remove is used instead.

Set-Mailbox -Identity "SharedMailbox@example.com" -GrantSendOnBehalfTo @{Remove="user1@example.com","user2@example.com"}

Best Practices

1. Audit Regularly: Regularly review and audit permissions to ensure they are still required and appropriate.
2. Least Privilege Principle: Grant permissions only to those who absolutely need them to minimize security risks.
3. Documentation: Keep documentation of who has been granted permissions and why, for compliance and tracking.
4. Use Groups for Multiple Users: If multiple users need the same permission, consider using security groups to manage permissions more efficiently.
5. Error Handling: Implement error handling in your scripts to catch and log any issues that occur during the execution of the commands.
6. Automate Routine Tasks: If permission changes are a frequent task, consider automating the process with scheduled scripts.
7. User Training: Ensure that users granted these permissions understand the implications and proper use of sending emails on behalf of others.

Conclusion

Managing SendOnBehalf permissions in Exchange Online using PowerShell provides a streamlined and efficient approach to email management. Whether you’re dealing with distribution lists or shared mailboxes, PowerShell offers the flexibility and control needed to handle these permissions effectively.

Remember: Always follow your organization’s policy regarding email permissions and ensure users understand their responsibilities when given such access.

Stay tuned for more insights and tips on leveraging PowerShell to manage Exchange Online and other Office 365 services!