models.MultipleEmailField

from django.core.validators import validate_email
from django.core.exceptions import ValidationError
from django.utils.translation import ugettext as _
from django.db import models

def multiple_email_validator(value):

    emails = value.split(',')
    for email in emails:
        try:
            validate_email(email.strip())
        except ValidationError as e:
            raise ValidationError(_(u'Enter a valid e-mail address separated by commas.'), code='invalid')

class MultipleEmailField(models.CharField):
    default_validators = [validators.multiple_email_validator]
    description = _("Multiple e-mail address")

    def __init__(self, *args, **kwargs):
        kwargs['max_length'] = kwargs.get('max_length', 512)
        super(MultipleEmailField, self).__ini__(*args, **kwargs)

    def formfield(self, **kwargs):
        raise NotImplementedError("here you can return a custom forms.MultipleEmailField")

class MyModel(models.Model):

    mymultipleemail = MultipleEmailField()