unable to delegate exchange online to exchange onpremises mailbox in hybrid enviornment.

Nur Hossain 282 Reputation points
2021-01-06T10:06:05.267+00:00

we have an Exchange hybrid environment, we are facing an issue while trying to delegates exchange online users to exchange on-premises mailbox.

Example: User A is an exchange online user (migrated from on-premises) and user B is an exchange on-premises user.

Now we want delegate user A to user B for send on behalf/full access but user A is unable to send mail on be half of user B.

Any idea?

Thank You
Nur

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
4,205 questions
Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
7,364 questions
Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
1,900 questions
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  1. Ashok M 6,506 Reputation points
    2021-01-06T12:13:33.75+00:00

    Hi,

    Could you please let us know how the mailbox permission has been assigned?

    Exchange hybrid deployments support the use of some delegated permissions in on-premise Exchange, but not all.
    https://learn.microsoft.com/en-us/exchange/permissions#delegate-mailbox-permissions

    In order for this permission to work, you may need to upgrade Azure AD connect to at least version 1.1.553.0. Also Enable Exchange Hybrid to writeback the permissions.

    https://learn.microsoft.com/en-us/exchange/troubleshoot/send-emails/delegate-cannot-send-on-behalf-of-after-migration

    If the above suggestion helps, please click on "Accept Answer" and upvote it

  2. Lucas Liu-MSFT 6,161 Reputation points
    2021-01-07T03:16:51.787+00:00

    Hi @Nur Hossain ,
    I agree with what AshokM-8240 said.

    1. What’s the on-premises Exchange version? You could follow the "Configuring your on-premises Exchange servers to support hybrid mailbox permissions" section in the first link provided by AshokM-8240 to check your on-premises Exchange version.
    2. Please make sure that your Azure Active Directory (Azure AD) Connect version to 1.1.553 or a later.
    3. After you have assigned permissions, it may take a while to work, please wait 30 minutes and try again.
      Here is an official document about delegation settings in the Exchange hybrid environment: Overview of delegation in an Office 365 hybrid environment

    Below screens is the test in my lab environment, User1 is the mailbox migrated to Exchange Online. Assign the send on behalf of permission of on-premises mailbox user2 to user1. Then user1 can send mail on behalf of user2 successfully
    54207-2222.png
    54225-3333.png

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