How to validate an email address in PHP

Question

I have this function to validate an email addresses   function validateEMAIL  EMAIL         v      a-zA-Z0-9 -      a-zA-Z0-9-    a-zA-Z           return  bool preg match  v   EMAIL       Is this okay for checking if the email address is valid or not

User · Answer

I think you might be better off using PHP s inbuilt filters - in this particular case   It can return a true or false when supplied with the FILTER VALIDATE EMAIL param

User · Answer

In my experience  regex solutions have too many false positives and filter var   solutions have false negatives  especially with all of the newer TLDs    Instead  it s better to make sure the address has all of the required parts of an email address  user      symbol  and domain   then verify that the domain itself exists   There is no way to determine  server side  if an email user exists for an external domain   This is a method I created in a Utility class   public static function validateEmail  email           SET INITIAL RETURN VARIABLES           emailIsValid   FALSE          MAKE SURE AN EMPTY STRING WASN T PASSED          if   empty  email                            GET EMAIL PARTS                   domain   ltrim stristr  email                                     user     stristr  email       TRUE                   VALIDATE EMAIL ADDRESS                  if                                        empty  user   amp  amp                       empty  domain   amp  amp                      checkdnsrr  domain                                      emailIsValid   TRUE                     RETURN RESULT          return  emailIsValid

User · Answer

The easiest and safest way to check whether an email address is well-formed is to use the filter var   function   if   filter var  email  FILTER VALIDATE EMAIL            invalid emailaddress     Additionally you can check whether the domain defines an MX record   if   checkdnsrr  domain   MX             domain is not valid     But this still doesn t guarantee that the mail exists  The only way to find that out is by sending a confirmation mail     Now that you have your easy answer feel free to read on about email address validation if you care to learn or otherwise just use the fast answer and move on  No hard feelings    Trying to validate an email address using a regex is an  impossible  task  I would go as far as to say that that regex you have made is useless  There are three rfc s regarding emailaddresses and writing a regex to catch wrong emailadresses and at the same time don t have false positives is something no mortal can do  Check out this list for tests  both failed and succeeded  of the regex used by PHP s filter var   function   Even the built-in PHP functions   email clients or servers don t get it right  Still in most cases filter var is the best option   If you want to know which regex pattern PHP  currently  uses to validate email addresses see the PHP source   If you want to learn more about email addresses I suggest you to start reading the specs  but I have to warn you it is not an easy read by any stretch    rfc5322 rfc5321 rfc3696 rfc6531  allows unicode characters  although many clients   servers don t accept it    Note that filter var   is as already stated only available as of PHP 5 2  In case you want it to work with earlier versions of PHP you could use the regex used in PHP    lt  php   pattern                 x22   x5C   x00-  x7E   x22        x22     x5C  x22   x22    255              x22   x5C   x00-  x7E   x22        x22     x5C  x22   x22    65             x21  x23-  x27  x2A  x2B  x2D  x2F-  x39  x3D  x3F  x5E-  x7E         x22      x01-  x08  x0B  x0C  x0E-  x1F  x21  x23-  x5B  x5D-  x7F       x5C   x00-  x7F      x22                 x21  x23-  x27  x2A  x2B  x2D  x2F-  x39  x3D  x3F  x5E-  x7E         x22      x01-  x08  x0B  x0C  x0E-  x1F  x21  x23-  x5B  x5D-  x7F       x5C   x00-  x7F      x22                     64            xn--   a-z0-9     -  a-z0-9         1 126   1         a-z  a-z0-9          xn--  a-z0-9       -  a-z0-9                  IPv6        a-f0-9  1 4      a-f0-9  1 4   7               a-f0-9         7       a-f0-9  1 4      a-f0-9  1 4   0 5         a-f0-9  1 4      a-f0-9  1 4   0 5             IPv6        a-f0-9  1 4      a-f0-9  1 4   5                a-f0-9    5       a-f0-9  1 4      a-f0-9  1 4   0 3         a-f0-9  1 4      a-f0-9  1 4   0 3              25 0-5      2 0-4  0-9      1 0-9  2       1-9   0-9               25 0-5      2 0-4  0-9      1 0-9  2       1-9   0-9     3          iD     emailaddress    test gmail com    if  preg match  pattern   emailaddress      1           emailaddress is valid     P S  A note on the regex pattern used above  from the PHP source   It looks like there is some copyright on it of Michael Rushton  As stated   Feel free to use and redistribute this code  But please keep this copyright notice

User · Answer

Use below code     Variable to check  email    quot john doe example com quot       Remove all illegal characters from email  email   filter var  email  FILTER SANITIZE EMAIL       Validate e-mail if  filter var  email  FILTER VALIDATE EMAIL       echo  quot Email is a valid email address quot      else     echo  quot Oppps  Email is not a valid email address quot

User · Answer

alnum      -           Nowadays  if you use a HTML5 form with type email then you re already by 80  safe since browser engines have their own validator  To complement it  add this regex to your preg match all   and negate it   if   preg match all         alnum      -           email            Find the regex used by HTML5 forms for validation https   regex101 com r mPEKmy 1

User · Answer

This will not only validate your email  but also sanitize it for unexpected characters    email      POST  email     emailB   filter var  email  FILTER SANITIZE EMAIL    if  filter var  emailB  FILTER VALIDATE EMAIL      false         emailB     email         echo  This email adress isn t valid        exit 0

User · Answer

If you re just looking for an actual regex that allows for various dots  underscores and dashes  it as follows   a-zA-z0-9 -     a-zA-z0-9 -    a-zA-Z    That will allow a fairly stupid looking email like tom anderson 1-neo my-mail matrix com to be validated

User · Answer

If you want to check if provided domain from email address is valid  use something like        Check for valid MX record for given email domain    if  function exists  check email domain         function check email domain  email              Get host name from email and check if it is valid          email host   explode       email                  Add a dot to the end of the host name to make a fully qualified domain name and get last array element because an escaped   is allowed in the local part  RFC 5322           host   end  email host                    Convert to ascii  http   us php net manual en function idn-to-ascii php          return checkdnsrr idn to ascii  host    MX       bool                   This is handy way to filter a lot of invalid email addresses  along with standart email validation  because valid email format does not mean valid email   Note that idn to ascii    or his sister function idn to utf8    function may not be available in your PHP installation  it requires extensions PECL intl    1 0 2 and PECL idn    0 1   Also keep in mind that IPv4 or IPv6 as domain part in email  for example user  IPv6 2001 db8  1   cannot be validated  only named hosts can   See more here

User · Answer

After reading the answers here  this is what I ended up with   public static function isValidEmail string  email    bool       if   filter var  email  FILTER VALIDATE EMAIL             return false               Get host name from email and check if it is valid      email host   array slice explode       email   -1  0           Check if valid IP  v4 or v6   If it is we can t do a DNS lookup     if   filter var  email host FILTER VALIDATE IP             flags    gt  FILTER FLAG NO PRIV RANGE   FILTER FLAG NO RES RANGE                      Add a dot to the end of the host name to make a fully qualified domain name            and get last array element because an escaped   is allowed in the local part  RFC 5322             Then convert to ascii  http   us php net manual en function idn-to-ascii php           email host   idn to ascii  email host                  Check for MX pointers in DNS  if there are no MX pointers the domain cannot receive emails          if   checkdnsrr  email host   MX                  return false                       return true

User · Answer

Answered this in  top question  about emails verification https   stackoverflow com a 41129750 1848217     For me the right way for checking emails is          Check that symbol   exists  and before and after it there are some non-  symbols                    Try to send an email to this address with some  activation code     When the user  activated  his email address  we will see that all is right          Of course  you can show some warning or tooltip in front-end when user   typed  strange  email to help him to avoid common mistakes  like no   dot in domain part or spaces in name without quoting and so on  But   you must accept the address  hello world  if user really want it       Also  you must remember that email address standard was and can   evolute  so you can t just type some  standard-valid  regexp once and   for all times  And you must remember that some concrete internet   servers can fail some details of common standard and in fact work with   own  modified standard     So  just check    hint user on frontend and send verification emails on given address

User · Answer

You can use filter var for this    lt  php    function validateEmail  email          return filter var  email  FILTER VALIDATE EMAIL          gt

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