Email subscribers when event happens

I’ve been searching through the documentation but still can’t figure out if what I need can be done.

So I would like to email all subscribers when an event happens. This event is not a scheduled event and could happen once a day, or once a month.

To be more specific, we are a tackle shop and we want to be able to notify customers who sign up for the service to get some sort of email/text? when we get fresh bait in. It would just be an all day event that would expire overnight and could even happen again the next day.

My research seems to point more towards notifications only for booking, but I hope I’m missing something.

Thanks!