Distribution List emails not fully delivering to an account, how do I resolve this?

Question

Distribution List emails not fully delivering to an account, how do I resolve this?

SIIA27 0

One of the users I work with stated they aren't getting every email from a Distribution List. I reset the profile, removed from the distribution list and readded, but the issue persists.

Kev Kelly 190 Reputation points

2023-07-17T14:49:58.4766667+00:00

Hi @SIIA27

If you perform a message trace for an email sent to the Distribution List, you should see the status "Expanded". If you drill into one of these messages, you should get the option to "View message in Explorer" which will take you to Explorer in the Microsoft 365 Defender portal

From within Explorer, you should get a breakdown of how/who the DL was expanded and the recipients that the email was sent too... is your impacted user listed/present? If so, what what does the "Latest delivery location" specify

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Kev Kelly 190 Reputation points

2023-07-17T14:49:58.4766667+00:00

Hi @SIIA27

If you perform a message trace for an email sent to the Distribution List, you should see the status "Expanded". If you drill into one of these messages, you should get the option to "View message in Explorer" which will take you to Explorer in the Microsoft 365 Defender portal

From within Explorer, you should get a breakdown of how/who the DL was expanded and the recipients that the email was sent too... is your impacted user listed/present? If so, what what does the "Latest delivery location" specify

Answer 1

Yuki Sun-MSFT 41,376 Moderator

Hi @SIIA27 ，

By "distribution list", are you referring to the contact list or contact group which is created in Outlook? See Create a contact group or distribution list in Outlook for PC.

If this is true, in order to narrow down if the issue is related to the "distribution list", please try sending a test mail directly to this user in question and see if the message can be received properly. If in this case they can get the mail, I'd recommend trying to setting up a new distribution list from scratch and check how it goes.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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SIIA27 0 Reputation points

2023-07-07T12:07:28.16+00:00

One of the clients I work with (I work with an MSP), and they are part of a distribution list (that's what area it's in in O365 admin). They've only gotten some of the emails but not all. I sent a test email from my account and it came in right away. Then, one of their coworkers sent a test email from the group, they never got that email. I've removed and re-added them and it didn't work.
Yuki Sun-MSFT 41,376 Reputation points Moderator

2023-07-11T07:59:03.0633333+00:00

One of the clients I work with (I work with an MSP), and they are part of a distribution list (that's what area it's in in O365 admin).

Hi @SIIA27 ，

Thanks for the clarification. So, it's a distribution list created by the admin from the admin portal, right?

I sent a test email from my account and it came in right away. Then, one of their coworkers sent a test email from the group, they never got that email.

Got a little confused here and want to confirm more about what exact problem you are encountering. Do you mean when a member of the distribution list send mails out as the distribution list, sometimes the mail can be received but sometimes not?

Please have a check using the Message Trace tool in EAC and see if any clues can be found.
SIIA27 0 Reputation points

2023-07-11T11:59:58.1633333+00:00

@Yuki Sun-MSFT I've run message traces on a few of the messages, nothing out of the ordinary, it's all the same thing, no discrepancies found in messages delivered and not. I added myself to that DL and had them send me an email from each person and I sent one as well. Everybody got it except for the person who is experiencing the issue.
Yuki Sun-MSFT 41,376 Reputation points Moderator

2023-07-12T07:19:12.7933333+00:00

Hi @SIIA27 ，

So, you mean the issue is that, the particular person cannot receive mails sent to the distribution list although he/she is indeed a member of the distribution list, right?

If there's no discrepancies in the message trace, I'd suggest searching within the user's mailbox and see if the mails are in other folders. You can also check the Junk mail folder in case the mails went there for any reason.
Yuki Sun-MSFT 41,376 Reputation points Moderator

2023-07-17T06:58:51.2666667+00:00

Hi @SIIA27 ，

Just checking in to see how things are going with this issue. Do you perhaps have any update to share?
SIIA27 0 Reputation points

2023-07-17T12:04:05.44+00:00

Haven't really resolved the issue here. Typically, we would at this point reach out to our software vendor to provide their support on this issue, but there isn't much unfortunately
Yuki Sun-MSFT 41,376 Reputation points Moderator

2023-07-19T09:04:36.2966667+00:00

Okay. Thanks @SIIA27 anyway for share the current status. If you still want to look into this issue, could you perhaps remove all personal information like email addresses and domain names, then share some screenshots of the message trace output so that we can understand better of the issue?
SIIA27 0 Reputation points

2023-07-19T12:09:20.3166667+00:00

@Yuki Sun-MSFT Unfortunately all emails in there are personal information and subject to HIPAA guidelines, so unfortunately I can't share that information
Yuki Sun-MSFT 41,376 Reputation points Moderator

2023-07-21T05:37:05.02+00:00

Hi @SIIA27 ,

It might be hard to go deeper on this without more details like a sample of the message trace, so, given this situation, probably it'd be better that you try reaching out to your software vendor so that they can troubleshoot further. Anywaysm should there's anything else we can help on this issue in the community platform, feel free to comment down.

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Distribution List emails not fully delivering to an account, how do I resolve this?

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