Save unsent messages and send them when you're back online

So I had sent a message to my friend, but I was offline. I closed the Discord app thinking that the message would be sent automatically once I got back online, but the next day I opened our chat and the message was completely gone. I think the message already gets resent if you stay on the app, but this doesn't seem to be the case if you close and reopen the app later.

Thank you!