How to check if an email address exists or not before sending emails? is there any paid or free APIs for this?

Professional email marketing systems often include a way to validate email addresses. This is typically NOT done at the time a message is sent out, for performance reasons. Instead, it's something that the user of the system can do before setting up the mailing. For example, at MailUp (http://www.mailup.com) we included in the Web admin console a way for the user to perform: a quick syntax check, which simply looks at the syntax of the email addresses (e.g. you imported a list collected at a trade show, and some of the addresses were entered without the @ or without a correct domain name, etc.) a DNS-based check, which looks at whether the domain name associated with that email account exists and is responding successfully You can then review the results and easily move them to the "Unsubscribed" list. The objective is always to send a message that has the lowest possible amount of bounces. That's because a poorly managed (or illegally obtained) list typically has a high number of bounces, and therefore the number of bounces is used as a "red flag" by email receivers (e.g. Gmail, Yahoo!, etc.) and can lead to deliverability issues.

Hey there!  I'd also recommend checking out http://briteverify.com - you can test our service right on our site and we'd be more than happy to run a test file free of charge to prove out the speed and accuracy of our service.  All of our lookups are in real time, direct with the actual email providers.  Please feel free to call/email me with follow up questions - contact info on our site.

Great question!  LeadSpend has technology that does just that - validates email addresses.  There are two ways two use our service: batch file cleaning and real-time, in-form validation.  For the batch file cleanse, you simply send us your list, we'll run it and then send you the results the next day. For real-time validation, we have an API with a JavaScript snippet that you add to your website.  It's really easy for a developer to implement and we have a team of folks on our side to help along the way. Pricing starts at just $0.01 per email address, with no long term commitment, and we have discounts based on volume  Our pricing is based on aggregated monthly volume, regardless of whether the data is processed in batches or in real-time via our API. Visit http://www.leadspend.com for more information!  Or email me: ali_at_leadspend_dot_com.

You can try this free approach. It pings the server of the email hosting provider and checks for an email. http://www.webdigi.co.uk/blog/2009/how-to-check-if-an-email-address-exists-without-sending-an-email/ Else, you have the aforementioned options..

There are a few simple methods if one has to check a single or couple of emails if they're valid or not by simply trying to login and click on forgot password. But it's  not a practical solution when it comes to bulk email verification. They are many websites while offer emails verification but most of them tend to send emails or ping the emails to check if they're valid or not. What I've come to observe is that more often than not these services fail to deliver accurate results. You could check this service (https://www.emailverifierapp.com/) which doesn't use the aforementioned method yet deliver accurate results.