Django - 发送关于模型更改的电子邮件

I want to send an email when a specific field is changed in a model. Is it possible? Here is what I am looking for. I have a profile model that includes a BooleanField that when the administrator selects to be true I want to send user an email. I know I could put it in a "def save(self):" but, that fires off an email anytime the model is changed and the field is true. Is there a way to have it only email if the field was changed from False to True? I want to send an email when a specific field i