Distribution list issue

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Distribution list issue

Sree 1,971

We are in a hybrid Exchange Infrastructure setup. Our nested DLs are still hosted in on-prem. We have migrated one of the DLs (#All IND - Subiaco) that is a member of "#Global IT - All" (by deleting the "#All IND - Sub" from the on-prem then recreating it in Exchange Online). And then we create an on-prem mailcontact with the external smtp address of " #ALLInd-Sub@ newmontmining.mail.onmicrosoft.com". It is also one of the alternate SMTP address of the migrated DL. If we sent an individual email to the on-prem mail contact, it is being redirected or sent to the migrated DL. But when we send emails to "#Global IT - All" which is a parent group of mail contact, the email is not being redirected to the migrated DL. We did a message trace but no result is showing.

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Answer 1

KyleXu-MSFT 26,396

@JustinMicheal-7973

I test it in my organization, I would send email successfully:

Create a group(OnlineList@keyman .onmicrosoft.com) on Exchange online.
Create this group as Mail contact on Exchange on-premises. Choose an non-synchronized Organizational unit for this Mail contact.
Add this Mail Contact to an Exchange on-premises group(******@domainlab.com).
Send email from Exchange on-premises mailbox, the email could send to Exchange online group successfully.

Here are detailed information about it:
Send to external from Exchange on-premises successfully:

Received from Exchange online:

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Sree 1,971 Reputation points

2021-09-21T12:35:51.89+00:00

This did not work for me
KyleXu-MSFT 26,396 Reputation points

2021-09-22T07:30:54.28+00:00

What is the detailed information about mail flow in your organization? You need to check in above way to know which step this email stopped.
Sree 1,971 Reputation points

2021-09-22T08:57:30.22+00:00

Our infra is a hybrid infrastructure.
We have Exchange 2016 in on-prem and Exchange Online.
User mailboxes are still synching from on-prem to Exchange online.
On the other hand, some of our DLs are still in on-prem and some are already pure cloud.
KyleXu-MSFT 26,396 Reputation points

2021-09-24T06:44:01.66+00:00

My lab is also in such topology, above commands could be used to check whether email are blocked.
Sree 1,971 Reputation points

2021-09-25T10:22:12.44+00:00

Please help me with the detailed commandlets
KyleXu-MSFT 26,396 Reputation points

2021-09-27T07:26:41.657+00:00
Here are they, you need to send a test email, then use commands below to check them(You need to change the value into the correct one in your organization):

Exchange On-premises: Get-TransportService | Get-MessageTrackingLog -Sender "******@domain.com" -MessageSubject "subject" -Start M/D/Y -End M/D/Y | Sort-Object Timestamp Exchange online: Get-MessageTrace -StartDate M/D/Y -EndDate M/D/Y -SenderAddress ******@domain.com | Sort-Object Received

For more detailed information about them, you could have a look about those two articles:

Get-MessageTrackingLog

Get-MessageTrace
Sree 1,971 Reputation points

2021-09-27T08:28:25.897+00:00

let me check with our OUs that are not synching.

One thing I noticed is that the mail-contacts that we have created are showing as a sync error in our AD connect.
Sree 1,971 Reputation points

2021-09-27T14:24:23.29+00:00

let me check with our OUs that are not synching.

One thing I noticed is that the mail-contacts that we have created are showing as a sync error in our AD connect.

should the online group in Exchange Online have the same email address with on-prem mail contact?
KyleXu-MSFT 26,396 Reputation points

2021-09-28T08:16:19.46+00:00

Yes, you need to use the same email address. So, you need to create this Mail contact in a non-synchronized OU. Otherwise, there will exist email address conflict.
Sree 1,971 Reputation points

2021-09-28T09:28:53.993+00:00

Ah no..

For this one, I thought that we shouldn’t sync the on-prem mail contact?
KyleXu-MSFT 26,396 Reputation points

2021-09-29T09:16:53.18+00:00

You could create a independent non-synchronized OU for this mail contact(Only have this one mail contact in it). It doesn't effect the using of other mail contact.
Sree 1,971 Reputation points

2021-09-29T11:05:18.733+00:00

sure ty testing it
KyleXu-MSFT 26,396 Reputation points

2021-10-04T07:39:38.457+00:00

@JustinMicheal-7973
I am writing here to confirm with you any update about this thread now? Could you send email successfully now?
If the above suggestion helps, please be free to accept it as an answer for helping more people.

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Distribution list issue

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