Offline Message Q

Im just wondering if you send an offline message to a contact thats offline, i mean muliple messages in the offline chat screen where you chat and type in all messages you want, then when you exit the chat screen after you typed all the messages you want them to receive, then when you go offline yourself (actually going offline and NOT appearing offline) will they recieve it? or do you have to be online, and wait for them to be online aswell so they will receive the chat screen with the messages you sent them when they were off, or you can go off after you seend offline message and they will still receive even if your offline yourself? thanks.