One of the questions asked most often by clients using Office 365 is whether there is the ability to send mail as an alias of their account. There are several well documented solutions to this problem, but it’s possible that even after doing things right, you wind up with an error of:

[callout]The following recipient(s) cannot be reached: ‘[email protected]’ on 11/27/2013 11:02 AM This message could not be sent. Try sending the message again later, or contact your network administrator. Error is [0x80070005-00000000-00000000]. [/callout]

You can scratch your head all day long trying to figure out if you did something wrong in the GUI or if you need to enter commands in PowerShell to fix it. Don’t worry, you probably did everything right. Outlook is to blame!


It turns out that Outlook has an old version of the offline address book cached. While these steps may vary a bit depending on your version of Outlook, I believe the steps should be fairly similar for Outlook 2013, Outlook 2010, and Outlook 2007.

To manually update the Offline Address Book (OAB), do the following:

  1. In Outlook, go to the Send/Receive tab and expand the Send/Receive Groups section, then click on Download Address Book…DownloadOfflineAddressBook
  2. Simply click OK on the defaults (assuming they look like the screenshot belowOfflineAddressBook
  3. You will see the following progress bar. Be warned, it can take a few minutes for it to go away, but let it do it’s thingOutlookSendReceiveProgress

Now you should be good to go in sending as a shared mailbox or distribution group. Give it a shot and let me know if you have any problems or questions and I’ll do my best to answer quickly. Thanks!