class BackForm(forms.Form):
    email = forms.CharField(widget=forms.EmailInput(attrs={'class':'form-control','placeholder':"请输入邮箱账号/手机号",'required':'email不能为空'}))
    password = forms.CharField(widget=forms.PasswordInput(attrs={'class':'form-control','placeholder':"请输入密码",'required':'password不能为空'}))

<form action="{% url 'send_mail' %}" method="post">
                {% csrf_token %}
            <ul>
            <li class="form-group has-error">{{ backform.email }}</li>
          </ul>
          <div>
            <input type="submit" class="btn btn-micv5 btn-block">提交</input>
          </div>
          <div class="tips-error bg-danger">错误提示</div>
            </form>

def send_mail(request):
    try:
        if request.method =='POST':
            backform = BackForm(request.POST)
            if backform.is_valid():