Exchange 2010: Receiving "You can't send a message on behalf of this user..." error when trying to configure delegate access

I am trying to give someone (John Doe) delegate access to another account (Jane Doe) in our test environment. However, I receive the following error from Exchange:

*Subject:* Undeliverable: You have been designated as a delegate for Jane Dow
*To:* Jane Dow

Delivery has failed to these recipients or groups:

John Doe
You can't send a message on behalf of this user unless you have permission to do so. Please make sure you're sending on behalf of the correct sender, or request the necessary permission. If the problem continues, please contact your helpdesk.


Diagnostic information for administrators:

Generating server: 

/O=UNIONCO/OU=EXCHANGE ADMINISTRATIVE GROUP (FYD132341234)/CN=RECIPIENTS/CN=jdoe
#MSEXCH:MSExchangeIS:/DC=local/DC=unionco:MAILBOX-1[578:0x000004DC:0x0000001D] #EX#

Can someone help me troubleshoot this?

In your question, you need to clearly define what you want to achieve.

There is a conflict between 'delegate rights' and 'Send As'.

Delegating rights can be anything from send-as, send-on-behalf, control calenders etc.

You need to ensure only either the client-side changes are made or the server-side changes are made, otherwise will cause you more trouble then ever.

I also recall a long time ago (might not be applicable now) that if you made changes to the client-side (aka Outlook), you need both users to be using the same version.

Personally any changes like these, i would do it on the Exchange server. The error message provides implies you are attempting to 'Send on Behalf'; therefore you need to:

1) Go to Recipient Management and choose Mailbox 2) Choose the mailbox and choose Properties in Action Pane 3) Go to the Mail Flow Settings Tab and choose Delivery Options 4) Click the Add button 5) Select the user who wish to grant access to and click Add and then Ok