when using one email account with multiple email address, how do you set up on Imap

Im trying to set up Email across all my apple devices using imap with my Blueyonder (Virgin Media) Account, i have one primary email address and login and then 6 emails attached to this account. before i have enterd all the email address in settings then seperated them with a coma ( I think this was on a pop setup) but i was only reciving some of my emails to the various devices. using imap i now get all mail to all devices. But can not send from the iduvidual email address.