When you try to add or remove SMTP addresses for distribution groups by using Exchange Admin Center (EAC) in a Microsoft Exchange Server 2013 environment, you receive the following error message:
Conversion from Microsoft.Exchange.Management.ControlPanel.EmailAddressItem to Microsoft.Exchange.Data.ProxyAddress has not been implemented.
This issue occurs because Windows PowerShell cannot identify the EmailAddressItem type.
To work around this issue, connect Windows PowerShell to the Exchange Online service, and then use the Set-DistributionGroup cmdlet to add or remove SMTP addresses.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about how to use Windows PowerShell in Exchange Online, go to the following Microsoft website:Set-DistributionGroup cmdlet, go to the following Microsoft website: