How to check if an email address exists without sending an email?

I had to use angle brackets <> with gmail. You will have to slightly change your instructions:
mail from: randomnonexist@gmail.com (with angle brackets)

Google came back with a long story saying that email address does not exist. Brilliant

A simple fsockopen command in PHP and you can open connection to any SMTP server with port 25.


$smtp_server = fsockopen("mail.reddit.com", 25, $errno, $errstr, 30);
fwrite($smtp_server, "HELO hi\r\n");
fwrite($smtp_server, "MAIL FROM: \r\n");
fwrite($smtp_server, "RCPT TO: \r\n");


The HELO line is supposed to contain the fully qualified domain name of the client. Using ‘hi’ for this purpose may result in a rejection before the address can be checked.

Some mail servers, e.g. Microsoft Exchange, will accept all email for any address and then generate their own bounce if the address is invalid.

It depends on how your mail server is setup. You can configure your mail server to accept any recipient and forward all mail that doesn’t match a user to a specific account.

As Capt. Sparrow mentioned with the Gmail servers, a lot more servers respond more kindly when the commands you send conform with RFC2821.

Brilliant idea, something to look into more depth. Some issues found during a couple of attempts: Gmail (At least the Google Apps servers) can take around 15 seconds to verify a domain, bit of pain but surely worth it. The larger services, Hotmail, Yahoo ect become tetchy if your servers IP doesn’t get a green light on Spamhaus.org so check your servers IP. HELO HI doesn’t always work but can be overcome with HELO as mentioned by Phil.

Only testing from my own connection I’ve been unable to carry out the whole process on the Yahoo and Hotmail servers because I’m on a dynamic IP thus blacklisted on Spamhaus.org.

It’s coming up with a place for this function to take place on a production site. With a lot of servers responding 250 even if the mail box doesn’t exist, then further verification is still required. If you were to request the server with both the requested email and a couple of random hashs, and all requests returned 250 then it’s likely the server is accepting any recipient, in which case you would still have to send a verification email out.

Still love the idea though, anything to take that extra step out of the users registration process is a good thing.

The point I think Brendan was trying to make above is that this is not a valid test that works in all situations. You will get a false 550 from some mail servers, if your MAILFROM address is unknown or is ruled to likely be SPAM by their anit-SPAM measures. Conversely, you will get false 250 responses from some servers that are configured as such. Positively acknowledging all email addresses removes a mechanism employed by spammers to discover what email addresses are valid within a domain. In my experience, I have never seen a mail server configured to not provide a positive response on a RCPT TO sent to the domain of the mail server.

If you want to check to see if the email address exists, then yes this works. However some people want to check to make sure the email address is valid before they, say — open a telnet session? (This is an action which could, after all, create human-perceivable delays in the app. It is also wholly impractical for servers that would have to repeat this action hundreds of times per second.)

I am continually shocked that noone knows the correct way of validating an email address in PHP. Here’s the code:

$email = getUserEmail();
$emailIsValid = filter_var($email, FILTER_VALIDATE_EMAIL);

That’s it. It only takes one line to validate an email. It will process emails correctly according to the RFC, which means “Screw you, I’m an ant-eater!”@example.com correctly passes the filter.

@Brendan
“It depends on how your mail server is setup. You can configure your mail server to accept any recipient and forward all mail that doesn’t match a user to a specific account.”

–> Can a mail server (any server such as MS Exchange) allow to forward all mails with the non-existent recipients to a specific account (as you mentioned) AND still return the error 550 5.1.1 as normal ? In other says, does the sender (from gmail for example) receive the error 550 5.1.1 after sending a mail to a mail server (Exchange for example) that has been configured to enable “forward rule” above ?

This solution is great for smaller organisations, but won’t work for larger organisations that use commercial spam and virus filtering services to clean their incoming mail. The MX records get changed to point to the filtering service, which does it’s filtering magic, then forwards the email to the organisations email server.

In fact, you can setup Exchange to accept and silently delete emails that are destined for non-existent mailboxes. This is a great way to stop dictionary attacks.

Validation is a check to ensure it is true to the specification (eg: is the number N digits long?). Not to be confused with verification which is a check to ensure it is correct within the intended system (eg: does the number work when phoned?).

This is verification, not validation.

Thanks.

Another way you could do this is actually send the email BUT let the user login as it has already activated his account and catch bounces. If an email of a user bounces then you just mark him as inactive and force him to re-enter a valid email upon login. It requires a bit more on the server side but helps you a great deal and makes the user’s life easier.

[...] FTP and SMTP are simple text based protocols. A previous article showed how to check if an email address exists using SMTP commands from the terminal. Here I would like to show you how you can use raw FTP [...]

There are also several Web Services that can validate an email address.

Hi,

I’ve used a class in PHP that does just that. I used the base from PHPClasses.org and extended the functionality a bit.

It searches for MX records and tries them, since some domains have multiple fall-back mechanisms etc. Most of the time it verifies correctly and is therefore reliable enough. I can’t distribute the code for it, since it is used within a company. But it works and indeed doesn’t take more than a second or two for each verification.

It also checks for valid HELO commands, since this is the first step to be allowed to proceed.

- Unomi -

Thanks for the article. After reading all the solutions to email validation – It seems this is the BEST and most obvious way is to validate the user. With that said, can anyone tell me how to make a BCC with php. I have tried everything and it only sends to my email and not the secondary email. I figure having the user reply to the confirmation proves they want to get the reply from my contact page. Adding BCC to the email headers doesn’t work for some reason. Any help would be apreciated.

I want to know if this email address is a valid one, I think I might be being scammed, if not that is good, but i need to know diplomatic@drivehq.com

Great, i have tested this on Gmail, yahoo mail and hotmail and it works.

Sweet.

Cheers

530 5.7.0 Must issue a STARTTLS command first. 5sm1835826yxd.35

I get above exception after mail from: command. – This is for particular email accounts that need a EHLO instead of standard HELO.

Just checked this to work with Gmail & Yahoo mail accounts. Great thanks for the detailed post.

Slightly diffferent subject but if I join a blog what will the people running the blog be able to tell about me, would they know where I was emailing from for example?

@Alex it is pretty easy to setup. Just download the PHP files in the “SMTP check code in PHP” make sure that it is working by just following the usage example.

I got it working in a few minutes on my LAMP server.

Hey very nice blog!!….I’m an instant fan, I have bookmarked you and I’ll be checking back on a regular….See ya

I have just tested with gmail .It seems it’s not work
telnet alt2.gmail-smtp-in.l.google.com 25
220 mx.google.com ESMTP x6si1141525gvf.28
helo hi
250 mx.google.com at your service
mail from: supermanxp2003@yahoo.com
555 5.5.2 Syntax error. x6si1141525gvf.28
mail from: supermanxp2003@yahoo.com
555 5.5.2 Syntax error. x6si1141525gvf.28

Could you help me .Thanks.Best regards

Thanks for reply quickly .
It’s worked well for me for gmail .But i have some problem with yahoo.It required authentication login .
telnet smtp.mail.yahoo.com 25
helo hi
mail from:
Could help me this one.Thanks
Best regards

Thanks for very helpful to replied.It’s also worked well for me for livemail.

Thank you for the great information. I have been searching for this question and finally got it.

In real terms the function:
$emailIsValid = filter_var($email, FILTER_VALIDATE_EMAIL);

doesnt work (does what is says on the tin but doesnt ‘check). This will allow anything that sits within standard. That means that anything that is correctly formatted will go through, doesnt have to be an actual valid address. For example xxx@staleproperty.com.uk will go through, it is valid because the RFC defines this as ok (allowing for future growth in the standard) but the reality is it is not valid because ‘.com.uk’ is not a valid base domain.

Thanks for sharing. It’s important information for SEO people.

I’ve just had an odd situation. I was buying an Apple product through Apple Finance (Barclays Bank). The tool they use to process the application validates the email address before accepting it. It failed to validate my email address on harper.org.uk and it also failed to validate my google mail address. I’ve also had issue with other companies attempting to validate email addresses and this validation failing for these two domains, particularly Vodafone’s Blackberry servers and an electronic magazine that I have attempted to subscribe to. There appears to be a common problem out there with email validation.

This is nice posting. Its helping to many friends say to me.
Doing good..

Thanks a lot..!

i got an error when run the script (Class ‘SMTP_validateEmail’ not found in D:\xampp\htdocs\mac\checkemailexamplephp.php on line 8)

please help

[...] 2) Usage example - DOWNLOAD [...]

[...] I have come across this PHP code to check email address using SMTP without sending an email. [...]

please verify this id………

Thanks for this useful trick. Unfortunately it does not work with the server I tried. It says:
554-….
554 Your access to this mail system has been rejected due to the sending MTA’s p
oor reputation. If you believe that this failure is in error, please contact the
intended recipient via alternate means.

Looks like there’s no workaround?

Wow, these code snippets are really good. I have been looking for a way to check if an email is valid on gmail! This code will be very helpful!

@newvalidate you have to download NET_DNS class drom PEAR library!!

I am having my IP reported as spammers !! how to solve this problem ?

For me I encountered a lot of problem to send a resume through internet because of some error flash of my yahoomail so what can i do for this …

I found the perfect tool:
gives you 5 free validation for an email with the headers!!!!

Thanks. simple and clear. I want to know is there any restriction to verify email addresses using this SMTP method.

I want to verify 1 million email addresses. is it possible??

Thanks in advance

Thanks for the snippet.

I’ll try to extend my service for detecting disposable email addresses (see block-disposable-email.com) with this kind of testing for the real existence of an email address as a second step. Unfortunately services like yahoo are always answering with “250″, so we have to assume that any email address exists there ..

Gerold

[...] telling me that the email address is valid. I also found this script, which is most accurate and most important reliable ? PHP [...]

Very nice guide, presented beautifully and easy to understand.

Dont know if there is anything wrong with my email address. If not how is it i cannot locate it and where do i access this. Having roblems cannot subscribe anywhere or receive emails. What am i doing wrong

ok so i took the python code from above and entered into my python idle shell script and got a syntax error??
COMMAND:
nslookup – q=mx bigcompanydomain.com

Good article. But this assumes that the smtp server runs on port 25 whcih may not be always true. for example, if the mail server uses secure SMTP, the port no will be 465 and we can’t get connection with simple telnet as it is secured.

If smtp is running on different port other than default (25), how to check this info? Any way using commands like nslookup?

my email id has been hacked now password is change how can i recover or delete my email id

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In the PHP download, there is the following statements:
// windows, we need Net_DNS
require_once ‘Net/DNS.php’;

Where can I download that include file?

I just love to add it at ysapak.com thanks for sharing it

This doesn’t work with servers that use alternative SMTP ports (465 or 587) and I doubt it works if SSL is required or passwords are required.

Great thanks to this usefull utility.
I have just a comment. If I call the fonction with the following sequence, it doesn’t work.
$email = ‘foo@gmail.com’;
$result = $SMTP_Valid->validate($email, $sender);

To be usable I have added this line in the function setEmails($emails) :
settype($emails, “array”);

Any reaction is welcome.