Will returning subscribers receive scheduled after opt-in messages sent to new subscribers?

If you've setup a scheduled after opt-in message, mobile phone numbers will only receive that message the first time they opt-in to the list. If customer subscribes to your list, then unsubscribes, then you create a scheduled after opt-in message, then that same customer re-subscribes, they still will not receive your scheduled after opt-in message, as it's only sent to customers where it's their first time subscribing to the list.