Include a Teams Channel Email Address in a DL to Make it Easier for Users to Email
Updated: January 2022
Following yesterday’s post about the email addresses used by Microsoft 365 Groups and Teams, including Teams channel email addresses, the following question was asked:
“I have an existing email address from my distribution list.
I am using this address for a Microsoft flow “send an email to a SharePoint list”.
The emails send to this email address I also want to place in a teams channel.
1. Can I use my existing email address as an alias from a team channel or
2. can I forward my email sent to the existing email address to a teams channel?“
In other words, we have an existing distribution list that we want to add a Teams channel email address as a member so that anything sent to the list is copied to the channel, including the capture of the messages and attachments in SharePoint.
Simple Solution – an Exchange Mail Contact
The simple solution is to create a new mail contact in Exchange Online using the email address for the channel. Go to the Recipients section of the (new or old) Exchange Admin Center (EAC), then Contacts, and add a new Mail Contact with the email address of the channel entered in the external email address property (Figure 1).
If you plan to allow people to email the distribution list from outside your organization, make sure to configure the distribution list to allow it to accept messages from unauthenticated senders. You can do this by editing the distribution list properties through the EAC, or by running the Set-DistributionGroup cmdlet to set the list’s RequireSenderAuthenticationEnabled property to $False:
Set-DistributionGroup -Identity "Teams DL" -RequireSenderAuthenticationEnabled $False
Exchange Online fully supports the addition of mail contacts in its distribution lists, so it’s an easy step afterwards to update the distribution list with the new contact. You can do this through the EAC or with PowerShell. For example, here’s how to add the contact created above to a DL.
Add-DistributionGroupMember -Identity "My DL" -Member "Teams911"
Any message now sent to the distribution list will be copied to the Team channel. If you don’t want the mail contact to show up in the GAL and OAB, set it to be hidden.
Set-MailContact -Identity Teams911 -HiddenFromAddressListsEnabled $True
More Complicated with Guest Accounts
You can also create a Azure Active Directory guest account for a teams channel email address and when you have the account set up, you can add that account to a distribution list. Exchange Online treats guests as mail users, which are a valid recipient type for email and supported as distribution lists members.
However, Exchange won’t deliver copies of messages sent to the distribution group to a guest member. The reason is that guest accounts don’t appear in Exchange address lists, so Exchange can’t check the validity of the recipient. Messages sent to the distribution list are delivered to all other members, but the guest account is a black hole.
The workaround is to add the guest to a Microsoft 365 group. Guest accounts are automatically added to the subscribers list of a Microsoft 365 group because email is the way they participate in conversations. If you then add the Microsoft 365 group to a distribution list, routing works as expected because when Exchange checks the recipients, it validates the Microsoft 365 group and not the individual members. Messages sent to a distribution group that include a Microsoft 365 group with a guest member pointing to a team channel work, but it’s a complicated approach when compared to the simplicity of using a mail contact.
For more information about distribution lists and mail contacts, go to Chapter 7 of the Office 365 for IT Pros eBook. And when you’ve read all that material, go on to Chapter 11 to learn about Microsoft 365 Groups and Chapter 13 to learn about Teams.
Thanks for this, I’d managed to get this far and it works great for delivering internal email to the channel. However we want email from outside the org to that DL to be posted to the channel too. Message tracking shows it delivered, but it’s not appearing in the channel. Have I missed something?
Nope. It should work. Do you have the checkbox set to allow people outside my organization to send email to the DL?
Same issue here! External email to DL is working fine.. but not delivered to Teams channel. Internal works and delivers to Teams channel.
I suppose I may have to use the O365 group workaround to get external working correctly?
Do you have any block on the domain used for Teams messages, like us.teams.ms or emea.teans.ms? That might stop messages getting through the Exchange transport system.
No.. if I email directly to the channel’s email address, it generates posts in Teams fine. But when this email is included as part of a DL, it goes into a black hole. I’m attempting the O365 group workaround now… setting up the Teams channel as a guest user, we get the invite emails as posts in Teams. Not sure how to add the O365 group as a member of the DL.. that doesn’t seem to be an option so far.
You should be able to add the group to a DL using PowerShell:
Add-DistributionGroupMember -Identity DL Member M365Group
That powershell command did work, for adding to the DL.
However, I still am not getting the email flow to work from external addresses.
I can email direct to the channel’s email address externally, and it posts fine.
But even emailing to the O365 group email directly (which has the channel guest account as a member) goes to a black hole.
Looking in message trace shows it expand the O365 group and then shows delivered to the channel email.. but no post in Teams 🙁
How odd. I fear it’s time to log a support call with Microsoft.
It looks like the message is leaving Exchange Online and has been delivered to the cloud-only mailbox used for the channel. A connector (from Teams) is supposed to pick up the message from there and post to Teams. You’re absolutely sure that the correct email address is being used?
I have the same setup with a DL that contains the @emea.teams.ms address to forward emails also to a Teams Channel.
It works for some E-mails sent to the DL and doesn’t work for others.
The sad thing is that there is no control over what happens after a mail gets sent to the channel address and not arrives in the channel.
I found this article: https://support.microsoft.com/en-us/office/send-an-email-to-a-channel-in-teams-d91db004-d9d7-4a47-82e6-fb1b16dfd51e
And it has one interestingpoint:
> Troubleshoot email failures
> The following are a few reasons why sending an email to a channel can fail:
> The email includes the channel email address as part of a distribution list. Make sure that the channel email address is being used directly.
If I read this correctly that you are now allowed to send mail to a teams channel via a DL.
Does not make sense, but could explain the behavior.
I’ve just tested this again and everything works perfectly.
I have a mail contact with its primarySMTPAddress pointing to the email address of a Teams channel.
The mail contact is a member of a DL.
Emails sent to the mail contact work.
Emails sent to the DL are delivered to the mail contact (Teams channel) along with the other members of the DL.
Having the mail contact correctly populated might be the key thing.
I have the same setup with a mail contact and the primarySMTPAdrress is the Teams Channel mail address.
What do you mean by “correctly populating the contact”?
The thing is that it works “most” of the time, but not all of the time and this makes it unreliable and cannot be trusted.
It should at least be possible to get the information that mails get discarded or do some kind of allow- or denylisting.
And why would MS put the information in a support article that email delivery to a channel via a DL “can” fail?