To Send-on-behalf of another user of a general department email address you must first be given permission to do so. If you are not sure if you have permission to send on behalf of a specific email address, please contact the owner of that email address or the Information Technology Help Desk if you do not know the owner of the email address. 

Once you have been given permission to send an email on behalf of someone else:

• Start a new mail message (click New)
• If you do not see a From box for you to click then:
• Click the Options tab
• Click Show From. This will cause the From field to display
  
• Click the From button and select Other E-mail Address...
  
• Type the email address or user name that you want to send on behalf of into the From box and click OK
  
• OR: Click on the From... button:
  
•  and then select the contact from your Global Address List and click OK.