Checking validity of email in django/python

Question

I have written a function for adding emails to newsletter base. Until I've added checking validity of sent email it was working flawlessly. Now each time I'm getting "Wrong email" in return. Can anybody see any errors here ? The regex used is :

\b[\w\.-]+@[\w\.-]+\.\w{2,4}\b and it is 100% valid (http://gskinner.com/RegExr/), but I may be using it wrong, or it may be some logic error :

def newsletter_add(request):
    if request.method == "POST":   
        try:
            e = NewsletterEmails.objects.get(email = request.POST['email'])
            message = _(u"Email is already added.")
            type = "error"
        except NewsletterEmails.DoesNotExist:
            if validateEmail(request.POST['email']):
                try:
                    e = NewsletterEmails(email = request.POST['email'])
                except DoesNotExist:
                    pass
                message = _(u"Email added.")
                type = "success"
                e.save()
            else:
                message = _(u"Wrong email")
                type = "error"

import re

def validateEmail(email):
    if len(email) > 6:
        if re.match('\b[\w\.-]+@[\w\.-]+\.\w{2,4}\b', email) != None:
            return 1
    return 0

Solution 1

UPDATE 2017: the code below is 7 years old and was since modified, fixed and expanded. For anyone wishing to do this now, the correct code lives around here.

Here is part of django.core.validators you may find interesting :)

class EmailValidator(RegexValidator):

    def __call__(self, value):
        try:
            super(EmailValidator, self).__call__(value)
        except ValidationError, e:
            # Trivial case failed. Try for possible IDN domain-part
            if value and u'@' in value:
                parts = value.split(u'@')
                domain_part = parts[-1]
                try:
                    parts[-1] = parts[-1].encode('idna')
                except UnicodeError:
                    raise e
                super(EmailValidator, self).__call__(u'@'.join(parts))
            else:
                raise

email_re = re.compile(
    r"(^[-!#$%&'*+/=?^_`{}|~0-9A-Z]+(\.[-!#$%&'*+/=?^_`{}|~0-9A-Z]+)*"  # dot-atom
    r'|^"([\001-\010\013\014\016-\037!#-\[\]-\177]|\\[\001-011\013\014\016-\177])*"' # quoted-string
    r')@(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+[A-Z]{2,6}\.?$', re.IGNORECASE)  # domain
validate_email = EmailValidator(email_re, _(u'Enter a valid e-mail address.'), 'invalid')

so if you don't want to use forms and form fields, you can import email_re and use it in your function, or even better - import validate_email and use it, catching possible ValidationError.

def validateEmail( email ):
    from django.core.validators import validate_email
    from django.core.exceptions import ValidationError
    try:
        validate_email( email )
        return True
    except ValidationError:
        return False

And here is Mail::RFC822::Address regexp used in PERL, if you really need to be that paranoid.

Solution 2

from django.core.exceptions import ValidationError
from django.core.validators import validate_email

value = "[email protected]"

try:
    validate_email(value)
except ValidationError as e:
    print("bad email, details:", e)
else:
    print("good email")

Solution 3

Ick, no, please, don't try to validate email addresses yourself. It's one of those things people never get right.

Your safest option, since you're already using Django, is to just take advantage of its form validation for email. Per the docs:

>>> from django import forms
>>> f = forms.EmailField()
>>> f.clean('[email protected]')
u'[email protected]'
>>> f.clean(u'[email protected]')
u'[email protected]'
>>> f.clean('invalid e-mail address')
...
ValidationError: [u'Enter a valid e-mail address.']

Solution 4

You got it wrong, but it is a task that you can't do anyway. There is one and only one way to know if an RFC 2822 address is valid, and that is to send mail to it and get a response. Doing anything else doesn't improve the information content of your datum by even a fractional bit.

You also screw the human factor and acceptance property, for when you give validateEmail my address of

[email protected]

and you tell me I've made an error, I tell your application goodbye.

Solution 5

I can see many answers here are based on django framework of python. But for verifying an email address why to install such an heavy software. We have the Validate_email package for Python that check if an email is valid, properly formatted and really exists. Its a light weight package (size < 1MB).

INSTALLATION :

pip install validate_email

Basic usage:

Checks whether email is in proper format.

from validate_email import validate_email
is_valid = validate_email('[email protected]')

To check the domain mx and verify email exists you can install the pyDNS package along with validate_email.

Verify email exists :

from validate_email import validate_email
is_valid = validate_email('[email protected]',verify=True)

Returns True if the email exist in real world else False.

View more solutions

Comments

[muntu]

fortunately this regex is not mine :) So you're also for the normal EmailField method ?

[msw]

I don't speak django, but the argument applies to any attempt to syntactically validate an address. code.djangoproject.com/ticket/3344 Looks like not even EmailField may be up to the task (but I didn't look real hard)

[cji]

that particular ticket is marked as fixed since 07/04/07, and bug there was in unicode handling of translated error message. I think that using Django validators is relatively safe now.

[Yogev Shelly]

Thanks, had an import with email_re (that's the snippet across the web) but your second code block did the trick

[jptsetung]

This is not valid anymore with the upcoming new top level domain extensions (more than 6 chars for the extensions I think) mashable.com/2011/06/21/icann-top-level-domains-change

[Imre Kelényi]

Here is a tiny Python module based on this method. Just use isEmailAddressValid(address) to perform the validation.

[kalefranz]

I believe there may be a bug in the email_re expression. Specifically in the quoted string line, I'm guessing the intent is that \001-011 should actually be \001-\011. Any thoughts?

[kalefranz]

Indeed, there is a typo in the code above. Source on github has since been fixed: github.com/django/django/blob/master/django/core/validators.‌​py Fair warning to those copying and pasting that regex.

[Luis Artola]

Since the question is about Django, this is the best answer. +1 for encouraging code reuse and simplicity.

[keithhackbarth]

This solution wasn't available back when the questions was originally asked, but is definitely the best answer.

[Jay Modi]

And still the best answer in 2017..! Forward to 2018..! This should be definitely accepted answer as per the current stream.

[Chidananda Nayak]

simple is better than complex , very good explanation

[Shubham Patel]

Best answer in 2018 and 2019. Forward to 2020..

[Divij Sehgal]

The update part is the best part. :D

[Rohit Kumar]

I believe this does not work for python 3 and only for python 2.

[romin21]

as e is not really needed here, unless you plan to use e.