If I send a Skype message to someone who is offline and then delete that person from my contact, will they still receive the message? Or do I have to wait until I'm sure they received it?

Skype used to have the little circle next to the message telling you whether or not someone received it, nowadays the other way to check that is to try to edit your message after 1 hour or so : if you can still edit it, that means they haven't seen it, if you can't edit it anymore, that means they've seen it.

Despite knowing this I don't actually know whether or not they will receive the message if I delete them after. Would anyone happen to know?