I'm creating a website for my business and I want to offer free first deliveries for the first week but I'm afraid people will take advantage of that.

I don't take any money or credit card info through the website, everything is done in person.

I was thinking of sending an email confirmation but it is very easy to keep making emails. I was also thinking of sending a text message with a 4 digit pin to enter but I have absolutely no clue how to do that. Is there any good method I could use.

  • 1
    I do have to say, that's an excellent question you posted here. Jul 10, 2015 at 1:14
  • The problem seems to be to prevent accounts taking advantage of the "free delivery in the first week", not necessarily to prevent "multiple accounts"? Can you not simply make sure the delivery address is unique?
    – MrWhite
    Jul 10, 2015 at 9:09
  • 2
    Why wouldn't you just see if you've delivered to X address. If you have, then don't offer it free. Am i misunderstanding this, or isn't this a simple solution?
    – Brandon
    Jul 15, 2015 at 19:51

3 Answers 3


Been dealing with this problem since 2001.

No good way.

Only option is to use Oauth 2.0 external authentications from Google/facebook/paypal and trust them to weed out duplicates.


I think the more you require in an account, the more difficult it is for one to reproduce it. By that, I mean you may want to require one's email address AND text messaging number and ask the user to confirm both pieces of information.

For the texting option, an easy way is to send a message less than 140 characters to a special MMS email address. Usually it consists of text that includes the new applicant's phone number followed by the @ then the cell provider domain.

Here's a URL that shows how to craft the email address:


While the texting option is a good idea, people can change phone numbers.

Personally, I think the only way to truly answer your problem is wait several years until computing devices come with fingerprint scanners and users can swipe their fingers to identify themselves. I'm not sure how long that would take, but it would be a good security idea.

  • BTW- We have fingerprint scanners on our laptops over 12 years ago and these were not the crappy ones either. Lenova, I think, still offers them as well as any manufacturer that deals in high security locales such as DoD.
    – closetnoc
    Jul 10, 2015 at 2:40

SMS Verification is a good idea, users have to be pretty committed to get duplicate phone numbers, bonus of giving you a database of your customers phone numbers for marketing purposes or following up after a period of time.

There's various ways to do this depending on how you're constructing the website, which CMS, etc.

One example in wordpress you could use this plugin - here's a tutorial: http://premium.wpmudev.org/blog/verify-your-wordpress-users-with-a-text-message

Here's another plugin that might be useful: http://codecanyon.net/item/simple-sms-verification/6037963

There might be free versions about, but personally I don't mind pay a small fee for a product that will save me hours of stuffing around.

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