Setting up additional accounts in Outlook is handy to get email from different servers.  You can use additional accounts to send email from those different mailboxes also.  But did you know that you can use this feature to send email from different email addresses that are set up on your Exchange server?  For example, if email messages you send come from example@example.com, but you also want to be able to send email from example@example.org.  Here is a step by step guide on how to do this in Outlook 2007:

  • Go to Tools->Account Settings
  • E-mail tab
  • New...
  • Next >
  • Manually configure server settings...
  • Next >
  • Internet E-mail
  • Next >
  • Enter your name, email address such as example@example.org
  • Account type POP3
  • Incoming mail server exchserver1.example.org
  • Outgoing mail server (SMTP) exchserver1.example.org
  • Enter username as <your domain>\<your username> and your domain password
  • If you save the password, you will have to update it here when you change it
  • You can choose the Test Account Settings...
  • It will get an error retrieving email using POP3, but we don't need that
  • Next >
  • Finish

At the bottom of the Accounts Settings window, be sure it is using your inbox for receiving messages. [more]

Go to Tools->Send/Receive->Send/Receive Settings->Define Send/Receive Groups
Edit the All Accounts group (and possibly any other groups) to exclude this account
This will prevent it from trying to retrieve email using POP3 all the time

Now, to send email from that email address, select that account from the Account dropdown under the Send button.