Ошибка импорта

def send_mail(self, to):
        kw = {
            "subject": u"Приглашение на сайт",
            "text_content": u"Здратвуйте, мы приглашаем вас на сайт",
            "to": to if not isinstance(to, (list, tuple)) else [to, ],
        }
        send_text_mail.apply_async(kwargs=kw)

from schooledit3d.celery import app
 
@app.task(ignore_result=True)
def send_text_mail(subject, text_content, to):
    message = EmailMultiAlternatives(subject=subject, body=text_content, to=to)
    message.send()

# coding: utf-8
from __future__ import absolute_import
 
import os
from celery import Celery
 
from django.conf import settings
 
# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'schooledit3d.settings')
 
app = Celery('schooledit3d')
 
# Using a string here means the worker will not have to
# pickle the object when using Windows.
app.config_from_object('django.conf:settings')
app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)

[2015-02-10 23:22:47,778: ERROR/MainProcess] Task apps.api.tasks.send_text_mail[6253cb1e-2515-4803-bdc1-992ea7aefda6] raised unexpected: ImportError("No module named 'django.core.mail.backends.smtp",)
Traceback (most recent call last):
  File "/home/ivan/virtualenvs/schooledit3d/local/lib/python2.7/site-packages/celery/app/trace.py", line 240, in trace_task
    R = retval = fun(*args, **kwargs)
  File "/home/ivan/virtualenvs/schooledit3d/local/lib/python2.7/site-packages/celery/app/trace.py", line 438, in __protected_call__
    return self.run(*args, **kwargs)
  File "/home/ivan/projects/Python/Django/schooledit3d/apps/api/tasks.py", line 15, in send_text_mail
    message.send()
  File "/home/ivan/virtualenvs/schooledit3d/local/lib/python2.7/site-packages/django/core/mail/message.py", line 286, in send
    return self.get_connection(fail_silently).send_messages([self])
  File "/home/ivan/virtualenvs/schooledit3d/local/lib/python2.7/site-packages/django/core/mail/message.py", line 247, in get_connection
    self.connection = get_connection(fail_silently=fail_silently)
  File "/home/ivan/virtualenvs/schooledit3d/local/lib/python2.7/site-packages/django/core/mail/__init__.py", line 37, in get_connection
    klass = import_string(backend or settings.EMAIL_BACKEND)
  File "/home/ivan/virtualenvs/schooledit3d/local/lib/python2.7/site-packages/django/utils/module_loading.py", line 26, in import_string
    module = import_module(module_path)
  File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
ImportError: No module named 'django.core.mail.backends.smtp