Unable to send email to distribution group "you dont have permssion" Exchange Hybrid setup.

Question

Hi, I am trying to add exchange online user to deligation tab on onprem exchange distributoin group properties but I cannot find the user exchange online user. I am trying to give access to a user who is exchange online user to be allowed to send email to our onprem email distribution group. Please help!

Answer 1

Is there a remote mailbox on-prem that represents the Exchange Online user? If not, create it: https://blog.expta.com/2016/05/creating-remote-mailbox-in-exchange.html

Answer 2

  Hi @ ATFRMZ ， Are you referring to granting users in Exchange online Full Access and Send As permissions in an on-premises distribution group?

In a hybrid environment, Microsoft 365 or Office 365  mailboxes can be granted full access and send on behalf  permission to on-premises shared mailboxes**.**

I recommend that you could refer to the following command line to see if you can add it:

Add-MailboxPermission -Identity <MailboxIdentity> -User <DelegateIdentity> -AccessRights FullAccess -InheritanceType All [-AutoMapping $false]

Set-Mailbox -Identity seanc@contoso.com -GrantSendOnBehalfTo hollyh

   

For permissions in the hybrid environment, please refer to this link: Permissions in Exchange hybrid deployments | Microsoft Learn

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Answer 3

I was able to add EXOmailbox user to On-Prem Distribution group under Delivery management and there after EXOmailbox user was able to send mail to this distribution group.

Answer 4

 Hi @ ATFRMZ ，

Sorry for the misunderstanding of this issue above. Here are some other suggestions I have for this issue:

Please run this command on-prem to check if the remote mailbox exists:

Get-RemoteMailbox -Identity user@contoso.com | Format-List

If so, try referring to this command to add it in delivery management to see if it works:

Set-DistributionGroup  -IgnoreNamingPolicy "True" -Identity "dg1" -AcceptMessagesOnlyFromSendersOrMembers ("user1")  -RequireSenderAuthenticationEnabled "False"

 

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