You do not need to assign a license to the shared mailbox in order to forward email that's sent to it. The mail-enabled security group must have at least one member. Any suggestions? For more information, see Create a distribution group naming policy. Am I missing something? Back at Servers > Virtual directories, select ecp (Default Web Site) on the server that you want to configure, and click Edit . Shared mailbox not receiving external messages I have a shared mailbox on an Exchange 2016 server. Automatically update email addresses based on the email address policy applied to this recipient: Select this check box to have the recipient's email addresses automatically updated based on changes made to email address policies in your organization. Select the name of the user (whose mailbox you want to allow to be read) to open their properties pane. Not possible. Only senders in your organization: When you select this option, only users or groups in your organization are notified when a message that they sent to the group isn't approved by a moderator. If you want to override your organization's group naming policy, see Override the distribution group naming policy. How to allow external users to send emails to a list in Office 365 This example configures the mailbox of Robin Wood to reject messages from the users Joe Healy, Terry Adams, and members of the distribution group Legal Team 2. Name: This name appears in the address book, on the To line when email is sent to this group, and in the Groups list. In this scenario, please try to create a new shared mailbox to check if the issue could be reproduced. For more information about internal and external URLs on virtual directories, see Default settings for Exchange virtual directories Virtual Directory Management. Convert a user mailbox to a shared mailbox (article) If you want to restrict inbound connections from external servers, modify the Default Frontend Receive connector on the Mailbox server. Send email from another person or group (article) Remove: To delete an email address associated with the group, select it in the list, and then click Remove . Under Members section, click View all and manage members to add/remove group members from the drop-down list and then click Save changes. In the Classic EAC, select the group and then click Edit to view the property or feature that you changed.