You do receive only three mails as warning and a last mail informing that the key has been deactivated. But you do receive those mails for each API key which is inactive for more than one year.

I forgot to write that we have generated several API keys - one per user - to keep our small platform sending SMS as simple as possible. Therefore, there are a lot notifications :D and I had the idea of a configuration section for the notification behaviour. But maybe we can create a small workaround for that.

The simplest way to avoid these notifications is to keep your api key(s) active. Just send a weekly/daily/monthly GET request to the /balance endpoint for example.

We don't want to get rid of this feature of expiring keys, because we like that idea that a member's key is deactivated when it wasn't used for a while. So that's fine. Therefore, we now simply filter the incoming warning mails as a workaround. :D