If a message fails to send, is it retried?

Yes. A failed message is retried a few times with widening gaps before it is finally marked failed. All sending runs through a background queue rather than inside a staff member's click, so no screen ever hangs waiting on a channel.

The queue is processed every few minutes, so "automatic" in Klasku means minutes, not seconds. A message status is only sent or failed — there is no read marker, because Klasku does not display what it does not actually know.