Sending emails with attachment in django

I'm trying to send email with some images attached in django. Code used is this snippet : http://www.djangosnippets.org/snippets/1063/. I don't know, why the attachment part returns me a core error.

The code. forms.py

from django import forms
from common import slugify_unique
from django.conf import settings
from django.core.cache import cache
from django.contrib.admin import widgets    
from django.shortcuts import get_object_or_404                                   

class WorkForm(forms.Form):
    name = forms.CharField(label='Name and surname', max_length=64, required = True )
    nick = forms.CharField(label='nickname', max_length=40, required = True )
    email = forms.EmailField(label='e-mail', required = True )
    image1 = forms.Field(label='sample photo', widget = forms.FileInput,    required = True )
    image2 = forms.Field(label='sample photo', widget = forms.FileInput, required = True )
    image3 = forms.Field(label='sample photo', widget = forms.FileInput, required = True )
    text = forms.CharField(label='Few words about you', widget=forms.Textarea, required = False )

views.py

from forms import WorkForm
from django.core.mail import send_mail, EmailMessage


def work(request):
    template = 'other/work.html'                             
    
    if request.method == 'POST':
        form = WorkForm(request.POST, request.FILES)
        if form.is_valid():
            name = form.cleaned_data['name']
            nick = form.cleaned_data['nick']
            email = form.cleaned_data['email']
            subject = 'Work'
            text = form.cleaned_data['text']
            image1 = request.FILES['image1']
            image2 = request.FILES['image2']
            image3 = request.FILES['image3']
            try:
                mail = EmailMessage(subject, text, ['EMAIL_ADDRESS'], [email])