If you are trying to add an additional email address to a distribution group in Office 365 using the web interface you will see the following error:
Conversion from Microsoft.Exchange.Management.ControlPanel.EmailAddressItem to Microsoft.Exchange.Data.ProxyAddress has not been implemented.
It is not a very helpful error message!
It is possible to work around this problem in web interface, but it is not simple. The easiest way to add the alias to the distribution group is by using Microsoft Powershell.
Adding an alias address to a distribution group in Office 365 using Powershell
I know that not everyone likes to revert to the command line for 365 administration – But I have made it very easy for you.
The email address is added by using the Set-DistributionGroup cmdlet, but all the powershell code you need will be created for you by filling out the boxes below:Group Name:
Email Address to add:
Simply copy and paste the text above into a Powershell Window and all the hard work will be done for you.
You will be prompted for your Office 365 credentials (make sure you enter credentials with permissions to edit the group) and then then your session will be established.
Then email alias will be added to the distribution group and you should be able to see it moments later in the web interface.
This is quite useful even if you are familiar with Powershell, saves on a lot of typing!