Permission & Access Issues

Fix Microsoft 365 Send As Delegates Randomly Removed from Distribution List

Chanuka Geekiyanage Oct 16, 2026 868 views

Question details

Users experience random removal of 'Send As' delegate permissions from a Microsoft 365 distribution list, resulting in message-sending errors.

How to Fix Microsoft 365 Send As Delegates Randomly Removed from a Distribution List

Product: Microsoft 365
Device & OS: not provided
Scenario: Managing distribution list permissions and delegates in a Microsoft 365 environment.
Observed behavior: Send As permissions unpredictably disappear from the distribution list on the backend without manual administrator intervention, preventing delegates from sending messages on behalf of the list.

Before you start

Ensure you have Exchange Online Administrator privileges and access to the Microsoft 365 Purview portal or PowerShell to review audit logs.

Solution 1Recommended

Review Audit Logs to Identify Permission Changes

Check the Microsoft 365 audit logs to determine if a specific administrator, policy, or synchronization process is overwriting the delegate list.

In many cases, delegates disappearing from a distribution list is caused by automated synchronization tools (like Azure AD Connect) or backend policies inadvertently overwriting manual changes. Reviewing the audit logs will help pinpoint the exact source of the removal.

Access the Compliance Portal

Navigate to the Audit Page

From the left navigation pane, select the 'Audit' tab.

Search for Mailbox Activities

Configure your search criteria by selecting 'Exchange mailbox activities' and specify the date range when the delegates were removed. Look specifically for changes to recipient permissions.

Analyze the Results

Click 'Search' and review the generated logs. Identify the user account or automated process (such as a directory sync service account) that triggered the 'Send As' permission removal.

Review Audit Logs to Identify Permission Changes

Directory Synchronization: If you discover that the Azure AD Connect sync account is making the changes, you must manage these permissions in your on-premises Exchange environment rather than the cloud, as the local AD is acting as the source of truth.

Solution 2

Re-add Permissions Using Exchange Online PowerShell

Use Exchange Online PowerShell commands to bypass potential Microsoft 365 Admin Center UI glitches and enforce Send As permissions accurately on the backend.

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Frequently Asked Questions

Is there a limit to the number of 'Send As' delegates a Microsoft 365 distribution list can have?

There is no restrictive standard limit that would cause delegates to randomly drop off when managing a typical list (e.g., 20-50 users). Disappearances are almost always caused by backend synchronization issues or conflicting automated policies rather than capacity limits.

Why do Microsoft 365 distribution list permissions disappear after a directory sync?

If you are using Azure AD Connect in a hybrid environment, on-premises Active Directory attributes act as the source of authority. This means they will overwrite any cloud-only changes during synchronization. To fix this, ensure you are managing the permissions in the on-premises Exchange Admin Center.

How long does it take for 'Send As' permissions to take effect in Exchange Online?

After adding a delegate using the Exchange Admin Center or PowerShell, it can take anywhere from a few minutes up to 24 hours for the 'Send As' permissions to fully propagate across the Microsoft 365 backend and take effect in the users' Outlook clients.

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