How to quickly check a large number of email addresses for validity


I have about 1000 people who answered a survey about 10 years ago that were interested in the product I was going to develop. They indicated they'd like me to send them an email when the beta release was out.

Obviously it took a long time (10 years), but I finally am in beta and want to send them that email.

However, I don't want to send them all out without quickly getting rid of the obviously bad email addresses. After 10 years, I expect 80% of the emails will have changed and will bounce back to me. My ISP service would not appreciate that many bounces from one mailing.

So is there a fast and simple way to pre-check the email addresses prior to sending them?


asked Feb 8 '10 at 07:54
1,471 points

4 Answers


If you have a winxp machine, you can use products like this. All it does is confirm the availability of a domain and the existence of an email address. Throttle the requests and your ISP shouldn't get angry.

answered Feb 8 '10 at 14:50
Jim Galley
9,952 points
  • 200 bounced messages is not that huge where it will trigger an alarm. Throttling is a good option. – Abdu 14 years ago


I really was looking for an automated way of doing it, preferably on my website with PHP. Something like this: "Verify a User's Email Address Using PHP ", but I had a lot of trouble getting that to work.

I ended up informing my email host that I'd be sending out these emails just one time and expected a lot of bounces. They allowed it. The emails went out and about 70% bounced, allowing about 300 people to get my product information.

answered Oct 17 '10 at 12:42
1,471 points


There are services that will do this via an API, either in real-time (one at a time) or bulk (list/batch) mode.

Examples include ( ), (Experian QAS ), and (StrikeIron ), among others. Rates and results vary, but integration is generally pretty straightforward.

answered Nov 5 '13 at 07:28
Josh Sam Bob
1,578 points
  • did you collect experience with this services? would you pass a account verification email (includes a account activation link), because these services are trustful? – Frank L 10 years ago
  • I don't know that you'd need to pass that info - you could just pass the email address, receive the response, and then pass back the activation link. Yes, I've had experience with them, and found them to be secure. The APIs are about as secure as they come. – Josh Sam Bob 10 years ago


Try utility ping.

Otherwise if you are good with linux then you can write your own perl or unix script.

answered Feb 8 '10 at 08:16
Thom Pete
1,296 points
  • How does ping be used to confirm an email address existence? Ping is used to see if a server is live and that's not reliable because some firewalls block pings or the server has the service turned off. – Abdu 14 years ago

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