Using multiple exchange mailboxes in outlook 2010

evanstest used Ask the Experts™
I am using Microsoft Exchange online through the Business Productivity Online Services suite.

I have outlook 2010 installed on my PC.

I need to access several microsoft exchange email boxes through the single outlook 2010 profile.  I have followed instructions found on the web to configure additional exchange email accounts using the control panel mail account.  These configurations seem to complete ok with the new exchange mailboxes being automatically found, etc.

Now, when I go back to outlook, I can receive email on all three exchange email accounts as expected.  The problem comes when I try to send or reply to an email from one of the email accounts that is not set as default.

When I do this I get an undeliverable mail message with error:

You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission.

Can someone advise how I need to configure exchange online and/or outlook such that I can send and receive from each of the three exchange email accounts?

Thanks in advance.
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
Within Exchange Management Console, you need to grant Send As permissions to the additional mailboxes.
sorry - hit submit before I'd finished.

Right click on one of the new mailboxes and choose 'Manage Send As Permission' and follow the wizard
ckeshavSr. Infrastructure Specialist

You need to assign "Send As" permission on the additional mailbox to yourself to get that permission.
When sending a message, Exchange requires that an e-mail address(of Additional Mailbox) is resolved in the From field in Outlook

Note: The Send As permission is not granted until after replication has occurred. Replication times depend on your Microsoft Exchange and network configuration. To grant the permission immediately, stop and then restart the Microsoft Exchange Information Store service.

Follow the below procedure from technet to assign "Send As" permission

Use the EMC to manage Send As permissions for a mailbox

You need to be assigned permissions before you can perform this procedure. To see what permissions you need, see the "Send As permissions" entry in the Mailbox Permissions topic.

In the console tree, click Recipient Configuration.
In the result pane, select a recipient. You can manage Send As permission for the following recipient types:
       Discovery mailboxes
        User mailboxes
        Resource mailboxes
In the action pane, click Manage Send As Permission.
On the Manage Send As Permission page, select the users or groups to which you want to grant the Send As permission or from which you want to remove the permission.
Add   Click this button to open the Select User or Group dialog box. Use this dialog box to select the users or groups to which you want to grant the Send As permission.
Remove icon   Select a user or group, and then click this button to remove the Send As permission from that user or group.
On the Completion page, review the following, and then click Finish to close the wizard:
A status of Completed indicates that the wizard completed the task successfully.
A status of Failed indicates that the task wasn't completed. If the task fails, review the summary for an explanation, and then click Back to make any configuration changes.
Click Finish close the wizard.
Success in ‘20 With a Profitable Pricing Strategy

Do you wonder if your IT business is truly profitable or if you should raise your prices? Learn how to calculate your overhead burden using our free interactive tool and use it to determine the right price for your IT services. Start calculating Now!


Thanks all for your comments but I don't think these options are available to me using Microsoft Exchange Online?  At least if they are, I can't seem to find them.

Also, I don't quite understand the need to set up a "Send As" permission.  I have configured outlook 2010 to have three email accounts, one for each of the individual exchange online mailboxes.  My understanding was that each of the three accounts should now operate as separate accounts? i.e. that i can send and receive from each of them independently.

ckeshavSr. Infrastructure Specialist
No unless and until you have "Send As" permission you will not be able to do that.
You need to request to grant this access from hosting administrator.
Thanks for all comments.  Pointed me in the right direction. I found solution for Microsoft Exchange online as follows:

First thing you need to do is download the Microsoft Online Services migration tools.  These are available here:

After installing the tools, click on Start, All Programs, Microsoft Online Services, Migration, and click on Migration Command Shell.
At the PowerShell prompt, type a command with the following syntax.

Add-MSOnlineMailPermission -Identity -TrustedUser -GrantFullAccess $True -GrantSendAs $True

run the command.  You will be prompted to enter credentials of a site adminsitrator.  Do this and the permissions will then be set on the account.  This takes a while to propogate. I found about one hour but thereafter works fine.
ckeshavSr. Infrastructure Specialist



comments pointed me in correct direction but I needed to find final solution for Microsoft Exchange myself from other sources.

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial