How to Include a Teams Channel in an Exchange Distribution List

Following yesterday’s post about the email addresses used by Office 365 Groups and Teams, 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 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 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.

Creating a new Mail Contact in Exchange Online

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 because Exchange Online treats guests as mail users, a valid recipient type for email.

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 validate that the recipient is in fact valid. 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 an Office 365 group. Guest accounts are automatically added to the subscribers list of an Office 365 group because email is the way they participate in conversations. If you then add the Office 365 group to a distribution list, routing works as expected because when Exchange checks the recipients, it looks at the Office 365 group and not the individual members. Messages sent to a distribution group that include an Office 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 Office 365 Groups and Chapter 13 to learn about Teams.

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