Probably best not to, but if you try to send a message to an email that has unsubscribed, it will try to send out the contributor marked inactive email, which will trigger the error and get caught in an infinite loop.
We should check to see that the email we are sending a notification about is not the email that unsubscribed.
Steps to reproduce
We should check to see that the email we are sending a notification about is not the email that unsubscribed.