Django邮件发送失败：设置端口587却自动使用25端口

问题 #

我的Django项目目前无法发送邮件，3个月前代码运行完全正常。

配置信息（settings.py） #

DEBUG = True

EMAIL_HOST = 'smtp.gmail.com'
EMAIL_PORT: 587
EMAIL_HOST_USER = 'xyz@gmail.com'
EMAIL_HOST_PASSWORD = 'xyz'
EMAIL_USE_TLS = True

ALLOWED_HOSTS = []

视图代码（views.py） #

def index(request):
    """The home page."""

    # Send a message.
    if request.method != 'POST':
        # No data submitted; create a blank form.
        form_email = EmailForm()
        form_message = EmailMessageForm()
    else:
        # POST data submitted; proecess data.
        form_email = EmailForm(data=request.POST)
        form_message = EmailMessageForm(data=request.POST)
        if form_email.is_valid() and form_message.is_valid():
            try:
                email = Email.objects.get(text=request.POST['text'])
            except:
                form_email.save()
                email = Email.objects.last()
            
            message_db = form_message.save(commit=False)
            message_db.email = email
            message_db.save()

            message_owner = (
                f'New email on your website from {request.POST["text"]}',
                f"Email has been sent from: {request.POST['text']}\n\n"
                f"Full message:\n\"{request.POST['message']}\"",
                'settings.EMAIL_HOST_USER',
                ['my@gmail.com',],
            )

            message_guest = ('Your email has been sent',
                "Many thanks for getting in contact with me. Your message was "
                "successfully sent. I will reach out to you as soon as possible."
                f"\n\nYour message:\n\"{request.POST['message']}\"",
                'settings.EMAIL_HOST_USER',
                [request.POST['text'],],
            )

            send_mass_mail((message_owner, message_guest), fail_silently=False)

            return redirect('home:contact_thank_you')

    # Display a blank or invalid form.
    context = {'form_email': form_email, 'form_message': form_message}
    return render(request, 'home/index.html', context)

报错信息 #

请求方法：POST
请求URL：http://127.0.0.1:8000/
Django版本：4.1.5
异常类型：TimeoutError
异常信息：[WinError 10060] 由于连接方在一段时间后没有正确响应或连接的主机没有反应，连接尝试失败
触发位置：home.views.index

核心疑问：明明在settings.py里设置了端口为587，但实际发送时却使用默认的25端口，为什么配置没生效？该怎么解决？

解决方法 #

1. 修复settings.py的语法错误 #

EMAIL_PORT: 587使用了冒号，这是Python字典语法，不是变量赋值，Django无法识别这个配置，因此会 fallback 到默认端口25。把冒号改成等号即可：

EMAIL_PORT = 587

2. 修正视图中的发件人参数 #

视图里的message_owner和message_guest中，发件人写的是字符串'settings.EMAIL_HOST_USER'，这会被当成字面量邮箱地址，而非读取配置里的真实邮箱。需要先导入settings模块，再引用变量：

# 在views.py顶部添加导入语句
from django.conf import settings

# 修改消息的发件人部分，去掉引号
message_owner = (
    f'New email on your website from {request.POST["text"]}',
    f"Email has been sent from: {request.POST['text']}\n\n"
    f"Full message:\n\"{request.POST['message']}\"",
    settings.EMAIL_HOST_USER,
    ['my@gmail.com',],
)

message_guest = ('Your email has been sent',
    "Many thanks for getting in contact with me. Your message was "
    "successfully sent. I will reach out to you as soon as possible."
    f"\n\nYour message:\n\"{request.POST['message']}\"",
    settings.EMAIL_HOST_USER,
    [request.POST['text'],],
)

3. 检查Gmail的SMTP权限设置 #

当前Gmail默认禁用普通密码登录SMTP，需要根据账号状态调整：

• 若开启了两步验证：生成应用专用密码，替换settings里的EMAIL_HOST_PASSWORD。
• 若未开启两步验证：需开启“不太安全的应用访问”（不推荐，建议优先开启两步验证后使用应用专用密码）。

4. 测试SMTP连接可用性 #

可以用Python自带的smtplib测试端口587的连接情况，排查网络或权限问题：

import smtplib

try:
    server = smtplib.SMTP('smtp.gmail.com', 587)
    server.starttls()
    server.login('xyz@gmail.com', '你的应用专用密码')
    print("SMTP连接成功")
    server.quit()
except Exception as e:
    print(f"连接失败: {e}")

内容的提问来源于stack exchange，提问作者Maxwell