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I have thousands of users signed up in my site so I have a good amount of statistical data to analyze my problem for you.

In the sign up process of my website, the required fields are username, password etc. and there are TWO fields which are asking for email (email and confirmation of email, as usual.)

The problem is, that 26% (I just calculated it) of users are entering AND RE-ENTERING (at confirm your email field) wrong email address! I know what you thinking and they are NOT spammers. They are totally legitimate but use the wrong email addresses.

Examples of emails...

  • MARY@HOTMAIL.COM (no comment...)

These are just examples so you can have a laugh, the most of the wrong emails are just wrong addresses. I don't know why 26% of users just DON'T KNOW THEIR #e@$@# EMAIL!

  1. What percentage of your users are entering (and re-enter in confirm field) their email address?
  2. How can a desperate webmaster handle this situation? Of course I can't get in contact with these users, because I don't have their emails!

P.S.: Most of my users are of age 30-35+, and they are not English speakers. I can say that internet is about 10 years old (or less) popular in my country. In many cases, I can tell that the wrong email addresses belong to kids who have a better understanding of computers (for example their addresses ends with 1987, 95 etc.).

share|improve this question
up vote 6 down vote accepted

An easy way to detect bogus email addresses is to send an email to the address with a confirmation link inside. If the user doesn't click on the confirmation link their account is not activated and they can't use their website until they do. This will catch fake email addresses but not prevent someone from creating a throw away address. However, this will deter the vast majority of users who are abusing your system.

In your case, you can go deactivate everyone's account (probably after a set period of time) unless they confirm their email address. This will be inconvenient to your users but if these bogus email addresses are a real problem this will solve it. Then you can verify future members using the technique above.

If you use PHP you can use the checkdnsrr() function to see if MX records have been set up for the domain name in their email address. If they haven't, or the domain doesn't exist, you will know immediately. (It is possible that some domains do not have these records set up that are legitimate. But these are few and far between).

list(, $domain) = explode('@', $email_address);
if (function_exists('checkdnsrr') && !checkdnsrr($domain, 'MX'))
    // invalid email address
share|improve this answer
yes thats exactly what i am doing right now. in order to complete your sign-up proccess, you must enter a valid email adress, and a confirmation link is sended. but they are entering wrong email adresses! my problem is how can i get in touch with these people who entered wrong email adress, and they just waiting for eternity for the confirmation link to come. some of them are sending email angry saying my website is not sending the confirmation link to their adresses, i am tired of responding to them saying politely that they probably entered wrong email adress... – kari_kari Nov 25 '10 at 18:02
thanks for the php code, i ll take a serious look to this. lets hope the response is instant so i dont have to delay the signup proccess. – kari_kari Nov 25 '10 at 18:04
In those cases give them a chance to fix/change their email address and try again. – John Conde Nov 25 '10 at 18:06

If the problem is that your users don't know their own e-mail address, then there's really not too much you can do about that. John Conde's provided a very clever way to check if the entered domain is set up for email, which should filter out a lot of the bad addresses, but it doesn't guarantee that the user will remember the right address.

Now, you could spellcheck the email address to point out any typos to the user, as well as check for misspellings of common names and email domains by calculating Levenshtein distances, but this is still very hit-or-miss. Given the situation you've described, you may have more success emphasizing how important it is to put in the exact email address and let the user know that this is a huge problem amongst new signups. This should at the very least get rid of asdfasdf addresses.

Novice computer users often have a hard time grasping that many computer applications require precise input, and that "john.smith@com" is not the same as "john@smith.com". This is why they might think it's ok to guess their email address, and that as long as it's "close enough" the application will figure it out. If they understood that a single incorrect character renders the email address completely useless, that might prompt them to ask their kids or family IT guy for help.

Alternatively, you could just do away with the email confirmation and verify users another way. For example, SMS confirmations are increasingly common these days, and they have the benefit of eliminating spam or duplicate accounts. Simply text the user with a confirmation code or give them a code to text to the site.

Or, if knowing the user's email address is vital to the site, just reverse the confirmation process. At the end of the signup process, ask the user to send an e-mail with a particular subject line to the site. You can even provide a mailto link to simplify the process, so all they have to do is click the link and hit "send".

share|improve this answer
thank you for your answer, no fortunately i dont have asdasdasd addresses, just many users dont know their e-mail adresses. i will use the method provided by John Conde, and i will make a list of common typos mostly on the domain part. for example many users type very popular mail providers in my country but entering wrong tld (com) and vice-versa. so i know that johnsmith@hotmail.(nonexistentTLD) is wrong, i can immediately inform them. thank you again for your answer Lese! :) – kari_kari Dec 1 '10 at 16:57
correction: i dont have MANY adasdasda addresses... just a few ;) – kari_kari Dec 1 '10 at 16:59

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