Convert a distribution list to a shared mailbox in Exchange Online

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

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:

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

Create shared mailbox

1. Go to Recipients > Mailboxes > Add a shared mailbox .

2. 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.

3. Click Create to save your changes and create the shared mailbox.

Add users to the shared mailbox

1. 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.

2. In the Distribution list group flyout that opens, click View all and manage members.

3. Click Add members .

4. 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.

5. 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.

6. Select Save.

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

1. Go to Recipients > Mailboxes.

2. Select a mailbox and click Mailbox delegation

3. In the Manage mailbox delegation flyout that opens, click Edit .

4. 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.

5. 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.

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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 $_}
   

   For example:

   $u = "julia@contoso.com","laura@contoso.com"
   
   $u | foreach {Add-MailboxPermission -Identity Marketing -AccessRights FullAccess -User $_}
   

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

7. 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) Send As permission in the shared mailbox using the following syntax:

   Tip

   The variable $u from the previous step should already identify the former group members who need Send As permission on the shared mailbox, so you can reuse that variable in this step. Otherwise, use the same syntax as the previous step to identify new users: $u = "<UserOrGroupEmailAddress1>","<UserOrGroupEmailAddress2>",..."UserOrGroupEmailAddressN"

   $u | foreach {Add-RecipientPermission -Identity <SharedMailboxIdentity> -AccessRights SendAs -Trustee $_}
   

   For example:

   $u | foreach {Add-RecipientPermission -Identity Marketing -AccessRights SendAs -Trustee $_}
   

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

8. Use the Set-Mailbox cmdlet or the new EAC to configure other properties from the deleted group that weren't available when you created the shared mailbox in Step 4.

   For example, the following parameters are available on the Set-Mailbox cmdlet:

   • AcceptMessagesOnlyFrom
   • AcceptMessagesOnlyFromDLMembers
   • AcceptMessagesOnlyFromSendersOrMembers
   • BypassModerationFromSendersOrMembers
   • CustomAttribute1 to CustomAttribute10
   • EmailAddresses
   • ExtensionCustomAttribute1 to ExtensionCustomAttribute5
   • GrantSendOnBehalfTo
   • HiddenFromAddressListsEnabled
   • MailTip
   • MailTipTranslations
   • RejectMessagesFrom
   • RejectMessagesFromDLMembers
   • RejectMessagesFromSendersOrMembers
   • SendModerationNotifications

   The parameters that were mentioned in Step 4 on the New-Mailbox cmdlet are also available on the Set-Mailbox cmdlet.

   For detailed syntax and parameter information, see Set-Mailbox.

9. By default, messages sent from the shared mailbox by users with Send As permission aren't copied to the sender. To change the behavior so messages are copied to the sender, use the following syntax:

   Set-Mailbox -Identity <SharedMailboxIdentity> -MessageCopyForSentAsEnabled $true
   

   For example:

   Set-Mailbox -Identity Marketing -MessageCopyForSentAsEnabled $true
   

   For detailed syntax and parameter information, see Set-Mailbox.

10. Tell users to remove the deleted group entry from their AutoComplete list in Outlook. Even though the new shared mailbox and the deleted group have the same information, the current entry in the AutoComplete list is tied to the deleted group, so the current entry needs to be removed. For instructions, see Remove AutoComplete list entries one at a time.