Why doesn't EmailMultiAlternatives send email?

Question

Django

I'm trying to send an email to an email address with a pdf attachment. There are no errors, but the letter does not come to the mail. What is wrong with my code, please tell me?

email = EmailMultiAlternatives(
        'Subject here', 'Here is the message.', '[email protected]',
        ['[email protected]'])
    email.attach_file('nds.pdf')
    email.send()