SMTPServerDisconnected:Connection unexpectedly closed when using Django send email through zoho smtp server

Problem

I am using zoho's email and would like to send contact form through their smtp server.
But no matter what I tried, it alwasy returns: SMTPServerDisconnected:Connection unexpectedly closed.

SMTPServerDisconnected
Connection unexpectedly closed

Possible Solutions

I have visited these sites when dealing with this problem:

My codes when I have this problem

views.py

def contact(request):
    if request.method == 'POST':
        form = ContactForm(request.POST)
        if form.is_valid():
            cd = form.cleaned_data
            send_mail(
                cd['subject'],
                cd['message'],
                cd.get('email', '[email protected]'),
                ['[email protected]'],
            )
            return HttpResponseRedirect('/contact/thank-you/')
    else:
        form = ContactForm()
    return render(request, 'books/contact_form.html', {'form':form})

settings.py

EMAIL_USE_TLS = True
EMAIL_HOST = 'smtp.zoho.com'
EMAIL_PORT = 587
EMAIL_HOST_USER = '[email protected]'
EMAIL_HOST_PASSWORD = '********'
DEFAULT_FROM_EMAIL = EMAIL_HOST_USER
DEFAULT_TO_EMAIL = '[email protected]'

My new codes when problem solved

The only problem is that sender's email in the views.py is using cd.get('email', '[email protected]'). When the customer typed his email in the contact form, it will use the customer's email address as the sender's email, thus the connection will be closed. So I have to keep the sender's email consistant to the smtp user account, as shown in the views.py.

def contact(request):
    if request.method == 'POST':
        form = ContactForm(request.POST)
        if form.is_valid():
            cd = form.cleaned_data
            # Using send_mail
            msg = """
            New contact form received!
            Path: {}
            Name: {}
            Suject: {}
            Email: {}
            Message: {}
            """.format(request.path, cd['name'], cd['subject'], cd['email'], cd['message'])
            send_mail(
                cd['subject'],
                msg,
                '[email protected]',
                ['[email protected]',],
            )

            return HttpResponseRedirect('/contact/thank-you/')
    else:
        form = ContactForm()
    return render(request, 'books/contact_form.html', {'form':form})

No changes in the settings.py.

Here is what I received after changed the views.py:

New contact form received!
Path: /contact/
Name: fakename 
Suject: this is my subject 
Email: [email protected] 
Message: Hello, this is the message body.