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

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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

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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 example me com   res   re search        s               s     string re I  res group 1    This will take out example me com 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

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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    gt  gt  gt  from email utils import parseaddr  gt  gt  gt  parseaddr  foo example com         foo example com     gt  gt  gt  parseaddr  Full Name  lt full example com gt      Full Name    full example com     gt  gt  gt  parseaddr   Full Name with quotes and  lt weird chars com gt    lt weird example com gt      Full Name with quotes and  lt weird chars com gt     weird example com     And if the parsing is unsuccessful  it returns a two-tuple of empty strings    gt  gt  gt  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    gt  gt  gt  parseaddr  invalid example com     notice the comma       invalid example     gt  gt  gt  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    gt  gt  gt      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    gt  gt  gt  from dns resolver import query  gt  gt  gt  domain    foo bar google com  rsplit      1  -1   gt  gt  gt  bool query domain   MX    True  gt  gt  gt  query  example com    MX   Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt          dns resolver NoAnswer  gt  gt  gt  query  not-a-domain    MX   Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt          dns resolver NXDOMAIN   You can catch both NoAnswer and NXDOMAIN by catching dns exception DNSException   And Yes  foo bar google com is a syntactically valid address  Only the last   should be considered for detecting where the domain part starts

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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

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Email addresses are not as simple as they seem   For example  Bob O Reilly tag example com  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 example com        print  Invalid email

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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

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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   lt john doe example com gt   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

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from validate email import validate email is valid   validate email  example example com  verify True  print bool is valid    See validate email docs

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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

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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

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Found this to be a practical implementation       s       s        s

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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  example example com         check regex True  check mx True        from address  my from addr ess   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  quot tokens quot  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  or from Ubuntu apt-get install python3-dns

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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

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There is no point  Even if you can verify that the email address is syntactically valid  you ll still need to check that it was not mistyped  and that it actually goes to the person you think it does  The only way to do that is to send them an email and have them click a link to verify   Therefore  a most basic check  e g  that they didn t accidentally entered their street address  is usually enough  Something like  it has exactly one   sign  and at least one   in the part after the                          You d probably also want to disallow whitespace -- there are probably valid email addresses with whitespace in them  but I ve never seen one  so the odds of this being a user error are on your side   If you want the full check  have a look at this question     Update  Here s how you could use any such regex   import re  if not re match r     regex here       email       whatever   Python  3 4 has re fullmatch which is preferable to re match   Note the r in front of the string  this way  you won t need to escape things twice   If you have a large number of regexes to check  it might be faster to compile the regex first   import re  EMAIL REGEX   re compile r     regex here        if not EMAIL REGEX match email       whatever     Another option is to use the validate email package  which actually contacts the SMTP server to verify that the address exists  This still doesn t guarantee that it belongs to the right person  though

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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     john example com    python-list python org    wha t  1an ug  ly email com   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

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w     -      w     a-z  2 3

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Use this filter mask on email input  emailMask      w  -        amp               i

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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

[python] How to check for valid email address?

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