How to check for valid email address?

Question

Is there a good way to check a form input using regex to make sure it is a proper style email address? Been searching since last night and everybody that has answered peoples questions regarding this topic also seems to have problems with it if it is a subdomained email address.

Answer 1

import validator
is_valid = validate_email('[e-mail]',verify=True)
if (is_valid==True):
    return 1
else:
    return 0

See validate_email docs.

Answer 2

Email addresses are not as simple as they seem! For example, Bob_O'[e-mail], is a valid email address.

I've had some luck with the lepl package (http://www.acooke.org/lepl/). It can validate email addresses as indicated in RFC 3696: http://www.faqs.org/rfcs/rfc3696.html

Found some old code:

import lepl.apps.rfc3696
email_validator = lepl.apps.rfc3696.Email()
if not email_validator("[e-mail]"):
    print "Invalid email"

Answer 3

I found an excellent (and tested) way to check for valid email address. I paste my code here:

# here i import the module that implements regular expressions
import re
# here is my function to check for valid email address
def test_email(your_pattern):
pattern = re.compile(your_pattern)
# here is an example list of email to check it at the end
emails = ["[e-mail]", "[e-mail]", "wha.t.`1an?ug{}[e-mail]"]
for email in emails:
    if not re.match(pattern, email):
        print "You failed to match %s" % (email)
    elif not your_pattern:
        print "Forgot to enter a pattern!"
    else:
        print "Pass"
# my pattern that is passed as argument in my function is here!
pattern = r"\"?([-a-zA-Z0-9.`?{}]+@\w+\.\w+)\"?"   
# here i test my function passing my pattern
test_email(pattern)

Answer 4

If you want to take out the mail from a long string or file Then try this.

([^@|\s]+@[^@]+\.[^@|\s]+)

Note, this will work when you have a space before and after your email-address. if you don't have space or have some special chars then you may try modifying it.

Working example:

string="Hello ABCD, here is my mail id [e-mail] "
res = re.search("([^@|\s]+@[^@]+\.[^@|\s]+)",string,re.I)
res.group(1)

This will take out [e-mail] from this string.

Also, note this may not be the right answer.. But I have posted it here to help someone who have specific requirement like me

Answer 5

email validation

import re
def validate(email): 
    match=re.search(r"(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9]+\.[a-zA-Z0-9.]*\.*[com|org|edu]{3}$)",email)
    if match:
        return 'Valid email.'
    else:
        return 'Invalid email.'

Answer 6

The Python standard library comes with an e-mail parsing function: email.utils.parseaddr().

It returns a two-tuple containing the real name and the actual address parts of the e-mail:

>>> from email.utils import parseaddr
>>> parseaddr('[e-mail]')
('', '[e-mail]')

>>> parseaddr('Full Name <[e-mail]>')
('Full Name', '[e-mail]')

>>> parseaddr('"Full Name with quotes and <[e-mail]>" <[e-mail]>')
('Full Name with quotes and <[e-mail]>', '[e-mail]')

And if the parsing is unsuccessful, it returns a two-tuple of empty strings:

>>> parseaddr('[invalid!email]')
('', '')

An issue with this parser is that it's accepting of anything that is considered as a valid e-mail address for RFC-822 and friends, including many things that are clearly not addressable on the wide Internet:

>>> parseaddr('invalid@example,com') # notice the comma
('', 'invalid@example')

>>> parseaddr('invalid-email')
('', 'invalid-email')

So, as @TokenMacGuy put it, the only definitive way of checking an e-mail address is to send an e-mail to the expected address and wait for the user to act on the information inside the message.

However, you might want to check for, at least, the presence of an @-sign on the second tuple element, as @bvukelic suggests:

>>> '@' in parseaddr("invalid-email")[1]
False

If you want to go a step further, you can install the dnspython project and resolve the mail servers for the e-mail domain (the part after the '@'), only trying to send an e-mail if there are actual MX servers:

>>> from dns.resolver import query
>>> domain = 'foo@[e-mail]'.rsplit('@', 1)[-1]
>>> bool(query(domain, 'MX'))
True
>>> query('example.com', 'MX')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  [...]
dns.resolver.NoAnswer
>>> query('not-a-domain', 'MX')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  [...]
dns.resolver.NXDOMAIN

You can catch both NoAnswer and NXDOMAIN by catching dns.exception.DNSException.

And Yes, foo@[e-mail] is a syntactically valid address. Only the last @ should be considered for detecting where the domain part starts.