If you are a Distribution List Manager then you are responsible for managing your members list.  The below steps will assist you in keep your lists up to date.

Overview

If you are an owner of a Distribution List (DL), you can manage its members, owners and who can send to the list using Microsoft’s online management portal: the Exchange Admin Center (EAC).
This guide shows how to access the correct page.

Access the Exchange Admin Center, via Outlook on the Web

1. Go to: https://outlook.office.com
2. Select the Settings gear (top right).
3. In the left menu, click General.
4. Select Distribution groups.
5. On the right, click the link that says:
   “To manage distribution groups, visit this portal.”
6. This opens the Exchange Admin Center directly to your DLs.
7. Use the Members tab to make updates.
   1. View all and manage owners
   2. View all and manage members
8. Click Save when finished.

OR 

Go directly there by clicking this link:
https://admin.exchange.microsoft.com/?page=groups&form=owa_groups

Note: You must already be an owner of the DL to add or remove other owners.

Configuring Who Can Send to a Distribution List (DL)

Can Distribution List owner configure this?

Yes.  If you are listed as an owner of a cloud‑based Distribution List, you can configure who is allowed to send email to the DL directly in the Exchange Admin Center (EAC).

DL owners can now manage:

• Who can send to the DL
• Whether external senders are allowed
• Specific allowed senders
• MailTips
• Message approval (moderation)

These options are available under the Settings tab when viewing your DL in Exchange Admin Center.

Note: Owners cannot modify directory‑level attributes (e.g., aliases, hide‑from‑GAL). Those remain admin‑only.

What Send Restrictions Can Be Configured?

Who Is Allowed to Send to the DL

DL owners can choose from:

• Anyone in the organization
• Only members of the DL
• Only specific users or groups
• Authenticated senders only (blocks spoofing and external senders)

These settings are found under Settings → Delivery management.

HOW TO:

• In the Exchange Admin Center (see Access via Outlook on the Web (OWA))
• Under Groups I own, select your Distribution List from the Groups I own list.
• Go to the Settings tab.
• Click Edit delivery management.
• Under Senders options, choose one of the following:
  • Only allow messages from people inside my organization
  • Allow messages from people inside and outside my organization
• To restrict sending to specific people, select Search name or email box under Specified senders.
• Use the search box to add the users or groups who should be allowed to send.
  • If you add names here, only those senders will be permitted.
• Remove any names to clear restrictions.
• Click Save.

Allow or Block External Senders

DL owners can toggle whether people outside the organization can email the DL:

• Allowed — external partners/vendors can send
• Blocked — only internal users can send

This is controlled under Delivery management.

HOW TO:

• In the Exchange Admin Center.
• Under Groups I own, select your DL.
  Go to the Settings tab.
• Click Edit delivery management.
• Under Senders options, choose one of the following:
  • Only allow messages from people inside my organization (blocks external senders)
  • Allow messages from people inside and outside my organization (allows external senders)
• If you want to allow external senders but still restrict who can send, add specific users under Specified senders.
• Click Save.

Message Approval (Moderation)

DL owners can configure moderation settings under Settings → Message approval, including:

• Require moderator approval for all messages
• Require approval only for external senders
• Add or remove moderators
• Specify senders who bypass moderation
• Choose whether senders are notified when messages are rejected

All of these options are owner‑editable.

HOW TO:

1. Open the Exchange Admin Center.  Under Groups I own, select your DL.
   https://admin.exchange.microsoft.com/?page=groups&form=owa_groups
2. Go to the Settings tab.
3. Click Edit message approval.
4. To enable moderation, turn on Require moderator approval for messages sent to this group.
5. Under Group moderators, add the people who should approve messages.
6. To allow trusted senders to bypass moderation, add them under Add senders who don’t require message approval.
7. Under Notify a sender if their message is not approved, choose your preferred notification setting.
8. Click Save.

How to Request Changes That Require Admin Access

Most DL settings can now be managed by owners. However, if you need changes to:

• Email aliases
• Directory‑level attributes
• Hidden‑from‑GAL status
• Mail flow rules
• Conversion to another group type

Please submit a ticket to the IT Service Desk using the Related Service at the bottom of this article.

Include:

• The name of the Distribution List
• The change you need
• Any specific users or groups involved

IT will apply the changes and confirm once complete.

Related Services

Distribution Lists