Convert a distribution list to a shared mailbox in Exchange Online

Article
05/17/2024

Use the Exchange admin center (EAC) or Exchange Online PowerShell to convert an existing distribution list to a shared mailbox. Shared mailboxes make it easy for a group of people in your company to monitor and send email from a common account, such as info@contoso.com or support@contoso.com. When a person in the group replies to a message sent to the shared mailbox, the email looks like it was sent by the shared mailbox, and not by the person who replied.

Use the EAC to convert distribution list groups into shared mailboxes

Important

Prior to converting an existing distribution list group into a shared mailbox, replace your existing distribution list group's address with another address so that this distribution list group is free to be converted into a shared mailbox. An address being used for a distribution list group cannot be converted into a shared mailbox.

Once you've freed the existing distribution list group from the email address that's to be used for the shared mailbox, perform the following steps:

Create shared mailbox.
Add users to the shared mailbox.
Assign Full Access and Send As permissions to members of a shared mailbox

Create shared mailbox

Go to Recipients > Mailboxes > Add a shared mailbox .
Fill in the required fields:
- Display name: A display name based on your discretion
- Email address: Specifically the email address that was freed from the distribution list group.
Click Create to save your changes and create the shared mailbox.

Add users to the shared mailbox

Select the newly created shared mailbox by clicking anywhere in the row other than the button option that appears in the blank area next to the Group name column.
In the Distribution list group flyout that opens, click View all and manage members.
Click Add members .
In the Search members list text box, enter the names of the members who were part of the distribution list group that you had freed the email address from.
Once their names appear under Members, check the checkbox corresponding to the names of those persons you want to add as members of the shared mailbox.
Select Save.

Assign Full Access and Send As permissions to members of a shared mailbox

Go to Recipients > Mailboxes.
Select a mailbox and click Mailbox delegation
In the Manage mailbox delegation flyout that opens, click Edit .
To grant Full Access and Send As permissions, click Add members and then select the users you want to grant permissions to.

Note

The Full Access permission allows a user to open the mailbox as well as create and modify items in it. The Send As permission allows anyone other than the mailbox owner to send email from this shared mailbox. Both permissions are required for successful shared mailbox operation.
Click Save to save your changes.

Use Exchange Online PowerShell to convert a distribution list group into a shared mailbox

There's no automated method for converting a distribution group into a shared mailbox. This section describes the manual steps for creating a shared mailbox with the same members, email addresses, and similar properties as the group in Exchange Online PowerShell.

Caution

This procedure requires you to delete the distribution group before you create the replacement shared mailbox. Record as much information as you can about the group as described in the early steps of the procedure. You can also use the Microsoft 365 admin center and the new Exchange admin center (new EAC) to record information about the group.

The following commands serve two purposes:
- To see if the distribution group is a member of other groups. After you replace the group with a shared mailbox, you need to add the shared mailbox as a member of those groups.
- To record the members of the group that you're going to convert.
```
$dgs = Get-DistributionGroup -ResultSize unlimited

$dgs | foreach {Write-Output -InputObject `r`n,($_.Name),"Group Members",("-"*25); Get-DistributionGroupMember -Identity $_ -ResultSize unlimited}
```
For detailed syntax and parameter information, see Get-DistributionGroup and Get-DistributionGroupMember.
To record all properties of the distribution group to convert, use the following syntax:
```
Get-DistributionGroup -Identity <GroupIdentity> | Format-List
```
Where <GroupIdentity> is the name, alias, or email address of the group.

For example:
```
Get-DistributionGroup -Identity Marketing | Format-List
```
To reveal the full value of a truncated property, replace <PropertyName> with the property name, and then run the following command:
```
Get-DistributionGroup -Identity Marketing | Select-Object -ExpandProperty <PropertyName>
```
For detailed syntax and parameter information, see Get-DistributionGroup.
Delete the distribution group by using the following syntax:
```
Remove-DistributionGroup -Identity <GroupIdentity>
```
For example:
```
Remove-DistributionGroup -Identity marketing@contoso.com
```
For detailed syntax and parameter information, see Remove-DistributionGroup.
Create the replacement shared mailbox using the following syntax and property values from the deleted distribution group.
- At a minimum, set the PrimarySMTPAddress and DisplayName values of the new shared mailbox to the values from the deleted distribution group.
- When you create the shared mailbox, you can also set the following properties to match the deleted distribution group:
  - Name
  - Alias
  - ModerationEnabled (the default value is $false)
  - ModeratedBy (the default value is empty)
  - SendModerationNotifications (the default value is Always)
The additional properties that are available to configure in PowerShell after you create the shared mailbox are listed in Step 8.

This example creates a new shared mailbox with the name, alias, display name, and primary email address of the deleted distribution group.
```
New-Mailbox -Shared -Name Marketing -Alias marketing -DisplayName "Marketing Group" -PrimarySMTPAddress marketing@contoso.com
```
For detailed syntax and parameter information, see New-Mailbox.

Use the list of groups that contain the deleted group from Step 1 to add the shared mailbox as a member of any required distribution groups or mail-enabled security groups by using the following syntax:

$m = "<GroupEmailAddress1>","<GroupEmailAddress2>",..."<GroupEmailAddressN>"

$m | foreach {Add-DistributionGroupMember -Identity $_ -Member <SharedMailboxIdentity}

For example:

$m = "allemployees@contoso.com","announcements@contoso.com"

$m | foreach {Add-DistributionGroupMember -Identity $_ -Member marketing@contoso.com}

For detailed syntax and parameter information, see Add-DistributionGroupMember.

Use the list of members from the deleted group that you recorded in Step 1 to give valid mail-enabled security principals (mailboxes, mail users, or mail-enabled security groups) FullAccess permission to the shared mailbox using the following syntax:

$u = "<UserOrGroupEmailAddress1>","<UserOrGroupEmailAddress2>",..."UserOrGroupEmailAddressN"

$u | foreach {Add-MailboxPermission -Identity <SharedMailboxIdentity> -AccessRights FullAccess -User $_}