reply form address

i am trialing office 365, i have set up the account and have added 2 other email addresses, one is live mail and the other is hosted by 1and1.

when i reply to an email i need the from address to be the same as the address that received the email.  i have set up my account to do this 'Automatic' but it isnt working.

how can i get this to work?

thanks

richard