Question : Sending email from different email address on same domain

I'm setting up different email accounts for 2 of our users here.

What I need to do is have myself with my own email account and I need to be able to send from 2 different email addresses
The other user has his own email address and needs to be able to send from 3 other accounts

I followed this article http://www.experts-exchange.com/Software/Server_Software/Email_Servers/Exchange/Q_21505467.html?sfQueryTermInfo=1+address+differ+email+from+send
but whenever I send an email I get this response

Your message did not reach some or all of the intended recipients.

      Subject:      
      Sent:      7/30/2008 11:29 AM

The following recipient(s) could not be reached:

      XXXXXX on 7/30/2008 11:29 AM
            You do not have permission to send to this recipient.  For assistance, contact your system administrator.
            MSEXCH:MSExchangeIS:/DC=local/DC=XXXXXX:CFCGVM1

email name and domain have been replaced with XXXXX in case you are wondering for my company confidentiality

Any ideas?

Answer : Sending email from different email address on same domain

You need to setup rights in 2 places:
- full mailbox rights (to access the mailbox) - from the "exchange advanced" tab on mailbox rights.
- send as (to send messages as this user while logged on a different mailbox) - from the "Security" tab, as described in my first post.

n-joy