I've finally given up using Facebook messaging, I find it slow and clunky - however it is extremely useful in that if I am offline and someone sends me a message it pops up when I log back in.
I converted to an IRC channel and want to use it as a help channel for a group of 3d Printers but if you log out there is now ay of seeing what messages have been sent while you are offline. It will be a pain to idle most the time.
Is there anything out there that meets this gap?
You are looking for an IRC bouncer service. Some services also log anything that happens when you are not online through the bouncer.