shared mailbox restrictions

Glenn Maxwell 6,446 Reputation points
2022-09-28T21:26:16.183+00:00

Hi All

i am using exchange 2016 hybrid environment. i have two shared mailboxes, one is created in onprem and migrated to online.
other is created as remote shared mailbox from onprem.

These shared mailboxes sends emails and calendar invites to many users on daily basis.
i want to restrict users from sending emails to these shared mailboxes. but this shared mailbox should receive calendar accept invites or reject emails not other emails. is there any way to achieve this.

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Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
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Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
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  1. LilyLi2-MSFT 1,956 Reputation points
    2022-09-29T06:52:38.897+00:00

    Hi @Glenn Maxwell ,

    Do you mean to make a shared mailbox only receive or reject calendar invitation messages? If I understand the error, please correct me.

    If this is the case, you could set up mail flow rules:

    1. In EAC, navigate to Mail Flow > Rules, click + to create a new rule.
    2. In the New rule page that opens, click More options.
    3. Apply this rule if > The recipient > is this person, select shared mailbox.
    4. Do the following, select Reject Message.
    5. except if > message properties > contains the message type, select calendar.

    If an Answer is helpful, please click "Accept Answer" and upvote it.
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  1. Amit Singh 3,096 Reputation points
    2022-09-29T10:33:51.98+00:00

    Agree with @LilyLi2-MSFT

    Also According to my experience, if you are a global admin or exchange admin, you can assign Full Access permission to them. In this situation, they won't send emails from the shared mailbox. However, as the users with full access permission, they can create calendar items; delete, view. and change messages and so on, like the owners of that mailbox.

    Note: the sync could need some time. Please wait a while to check the result.
    For further reference about the permission of shared mailbox, there is the article:
    https://learn.microsoft.com/en-us/Exchange/collaboration/shared-mailboxes/shared-mailboxes?view=exchserver-2019

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  2. Glenn Maxwell 6,446 Reputation points
    2022-09-29T14:01:05.243+00:00

    shared mailbox should only receive or reject calendar invitation messages not any other emails.

    will this transport rule work.

    Name: Sent to sharedmailbox.
    Apply this rule if: This recipient is: sharedmailbox@Company portal .com
    Do the following: Reject the message with the explanation: Test
    Except if: The message type is Calendaring.