通过Django发送电子邮件会导致服务器错误（500）

Question

我正在尝试从管理员向填写表格并因此获得Server Error (500)的用户发送电子邮件。如何解决此错误？这是我的代码：（顺便说一句，当我在本地服务器上运行应用程序时，一切工作都很好，但是在IP上会出现错误）

views.py：

from django.shortcuts import render
from .models import Question, Message
from django.core.mail import send_mail
from django.conf import settings

def index(request): 
    context = {
        'questions': Question.objects.all()
    }
    if request.method == "POST":
        if request.POST.get('message_text'):
            Message.objects.create(
                sender_name = request.POST.get('sender_name'),
                sender_email = request.POST.get('sender_email'),
                message_text = request.POST.get('message_text'))

    if request.method == 'POST':
        sender_email = request.POST.get('sender_email')
        sender_name = request.POST.get('sender_name')
        subject = 'Welcome !'
        message = 'Dear ' + str(sender_name) + '! \n We will back to you.'
        from_email = settings.EMAIL_HOST_USER
        recipient_list = [sender_email]
        send_mail(subject, message, from_email, recipient_list)

    return render(request, 'index.html', context)

settings.py：

EMAIL_HOST = 'smtp.gmail.com'
EMAIL_USE_TLS = True
EMAIL_PORT = 587
SERVER_EMAIL = 'hi@mail.com'
EMAIL_HOST_USER = 'hi@mail.com'
EMAIL_HOST_PASSWORD = '******'