OK, it was a bit tough to come up with something that avoided all three of these words, but I tried to describe the benefit up front:
To protect your inbox, we’ve temporarily put email notifications on hold for today, as the maximum of %{count} per day was reached.
In reality we’re protecting everyone here, not just the user, as sending a ton of email causes spam-like problems in reporting, volume, traffic, etc. Also when self-hosting you do get charged per email, so it’s not free.
Keep in mind, out-of-the-box, we will send up to 100 emails a day, it sounds like you decreased max emails per day per user in the site settings to 10. Which is totally fine and up to you.
With such a low limit I would recommend adding a small note about how Discourse has a “mobile app” that supports push notifications. That way people that want more frequent notifications have a way to get them.