How to check for valid email address?

This is typically solved using regex. There are many variations of solutions however. Depending on how strict you need to be, and if you have custom requirements for validation, or will accept any valid email address.

See this page for reference: http://www.regular-expressions.info/email.html

Email addresses are incredibly complicated. Here’s a sample regex that will match every RFC822-valid address:
http://www.ex-parrot.com/pdw/Mail-RFC822-Address.html

You’ll notice that it’s probably longer than the rest of your program. There are even whole modules for Perl with the purpose of validating email addresses. So you probably won’t get anything that’s 100% perfect as a regex while also being readable. Here’s a sample recursive descent parser:
http://cpansearch.perl.org/src/ABIGAIL/RFC-RFC822-Address-2009110702/lib/RFC/RFC822/Address.pm

but you’ll need to decide whether you need perfect parsing or simple code.

The only really accurate way of distinguishing real, valid email addresses from invalid ones is to send mail to it. What counts as an email is surprisingly convoluted ("John Doe" <[email protected]>" actually is a valid email address), and you most likely want the email address to actually send mail to it later. After it passes some basic sanity checks (such as in Thomas’s answer, has an @ and at least one . after the @), you should probably just send an email verification letter to the address, and wait for the user to follow a link embedded in the message to confirm that the email was valid.

Email addresses are not as simple as they seem! For example, Bob_O’[email protected], 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("[email protected]"):
    print "Invalid email"

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('[email protected]')
('', '[email protected]')

>>> parseaddr('Full Name <[email protected]>')
('Full Name', '[email protected]')

>>> parseaddr('"Full Name with quotes and <[email protected]>" <[email protected]>')
('Full Name with quotes and <[email protected]>', '[email protected]')

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@[email protected]'.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@[email protected] is a syntactically valid address. Only the last @ should be considered for detecting where the domain part starts.

import re
def email():
    email = raw_input("enter the mail address::")
     match = re.search(r'[w.-]+@[w.-]+.w+', email)

    if match:
        print "valid email :::", match.group()
    else:
        print "not valid:::"

email()

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 [email protected] "
res = re.search("([^@|s]+@[^@]+.[^@|s]+)",string,re.I)
res.group(1)

This will take out [email protected] from this string.

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

"^[w.+-]+@[w]+.[a-z]{2,3}$"

I haven’t seen the answer already here among the mess of custom Regex answers, but…

There exists a python library called py3-validate-email validate_email which has 3 levels of email validation, including asking a valid SMTP server if the email address is valid (without sending an email).

To install

python -m pip install py3-validate-email

Basic usage:

from validate_email import validate_email
is_valid = validate_email(email_address='[email protected]', 
    check_regex=True, check_mx=True, 
    from_address='[email protected]', helo_host='my.host.name',  
    smtp_timeout=10, dns_timeout=10, use_blacklist=True)

For those interested in the dirty details, validate_email.py (source) aims to be faithful to RFC 2822.

All we are really doing is comparing the input string to one
gigantic regular expression. But building that regexp, and
ensuring its correctness, is made much easier by assembling it
from the "tokens" defined by the RFC. Each of these tokens is
tested in the accompanying unit test file.

you may need the pyDNS module for checking SMTP servers

pip install pyDNS

apt-get install python3-dns

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.'

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 = ["[email protected]", "[email protected]", "wha.t.`1an?ug{}[email protected]"]
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)

I see a lot of complicated answers here. Some of them, fail to knowledge simple, true email address, or have false positives. Below, is the simplest way of testing that the string would be a valid email. It tests against 2 and 3 letter TLD’s. Now that you technically can have larger ones, you may wish to increase the 3 to 4, 5 or even 10.

import re
def valid_email(email):
  return bool(re.search(r"^[w.+-]+@[w]+.[a-z]{2,3}$", email))

Finding Email-id:

import re 
a=open("aa.txt","r")
#c=a.readlines() 
b=a.read()
c=b.split("n")
print(c)
  for d in c: 
    obj=re.search(r'[w.]+@[w.]+',d)
    if obj:
      print(obj.group())  
#for more calcification click on image above..

For check of email use email_validator

from email_validator import validate_email, EmailNotValidError

def check_email(email):
    try:
        v = validate_email(email)  # validate and get info
        email = v["email"]  # replace with normalized form
        print("True")
    except EmailNotValidError as e:
        # email is not valid, exception message is human-readable
        print(str(e))

check_email("test@gmailcom")

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

See validate_email docs.

Found this to be a practical implementation:

[^@s]+@[^@s]+.[^@s]+

Use this filter mask on email input:
emailMask: /[w.-@'"!#$%&'*+/=?^_{|}~]/i`