奇怪的行为mock的side_effect函数

I have this piece of code:

我有这段代码：

import postie

def send_mail(self, outbox):
    try:
        postie.postmail(self.dbname, outbox)
    except postie.EmailDeliveryException:
        self.logger.error('Fail to send mail’)
        return False
    return True
import p