virtab

Email Checker’s Advanced email verification service completes a deep cleaning by performing an SMTP simulation test to check if the mailbox actually exists on the destination mail server for the best email validation accuracy.
Lets face it, people misspell their email address and are completely unaware of it, resulting in a delivery failure due to a bounce or maybe even a spam complaint. Furthermore, you also just lost a potential customer for your business! What is very interesting is most of these invalid email addresses are a result of a simple misspelled domain such as “hotmail.con”, “gnail.com”, or “yahoo.cmo”.
For example “jane@gmail.cmo” perfectly passes the <a href="https://codex.wordpress.org/Function_Reference/is_email" rel="nofollow ugc">is_email()</a> function, but does not really exist. Such addresses cannot escape Email Checker’s email verification test, ensuring you do not lose any valuable leads due to typos, as well as preventing spam signups by bots and more.
Email Checker can verify email addresses by detecting and revising typos, invalid syntax, invalid domain DNS, invalid MX DNS, disposable addresses, role accounts, free email providers, frequent complainers, offensive words, spam traps, honey pots, blacklists, catchalls, greylistings, mailbox exists, mailbox full and mailbox does not exist.
This email validation plugin integrates perfectly with other major plugins such as Contact Form 7, Gravity Forms, Ninja Forms and any other plugins that use the is_email() function. This plugin will validate email addresses in real-time and notify the user immediately so they can change it before submitting.
This plugin requires an Email Checker API Key and for credits to be purchased. You can create an account for Email Checker and purchase credits here: <a href="https://www.emailchecker.io" rel="nofollow ugc">Email Checker</a> (Signup in less than 30 seconds).
NOTE: You must have credits inside your <a href="https://www.emailchecker.io" rel="nofollow ugc">www.emailchecker.io</a> account in order for it to validate email addresses in your website’s forms.

Email Checker

Prevent spam signups by bots and lost customers in comment, registration, and contact forms using Email Checker's Email Verification Plugin.

zerobounce

Need an email validation tool to block invalid and high-risk emails on your WordPress website?
The ZeroBounce email verification plugin assists users by validating email addresses entered into your registration forms, comments sections, eCommerce shops, and more. Install the plugin, connect your API key, and select the forms you want to monitor with email validation.
<h3>Key Features</h3>
<ul>
<li>Automated real-time email validation – Automatically prevent selected email types from creating accounts, leaving comments, or signing up</li>
<li>Detect more than 30+ email address types – Including invalid, abuse, disposable, spam trap, toxic domains, catch-all, and more</li>
<li>Choose what to accept – Create your own rules for email validation and disallow emails based on status</li>
<li>Email verification for 9 form types – Easily select which forms you want to protect with email validation</li>
<li>Fast manual email validation – Verify any email address in the tools section using our interactive form</li>
<li>Email validation API logs – Keep track of monthly email verifications, including status, sub-status, IP, date, and credits used</li>
</ul>
<h3>Benefits</h3>
<ul>
<li>Keep your email list clean & accurate</li>
<li>Reduce your email bounce rate</li>
<li>Boost your inbox placement</li>
<li>Protect your email sender reputation</li>
<li>Improve email deliverability</li>
<li>Eliminate fraudulent, untrustworthy shoppers</li>
<li>Block spammers and spoofers</li>
<li>Keep your comments section clean</li>
</ul>
<h3>Supported Forms/Plugins</h3>
<ul>
<li>Contact Form 7</li>
<li>WPForms</li>
<li>Ninja Forms</li>
<li>Formidable Forms</li>
<li>WooCommerce</li>
<li>WordPress Post Comments</li>
<li>WordPress Registration</li>
<li>MC4WP: Mailchimp for WordPress</li>
<li>Gravity Forms</li>
<li>Fluent Forms</li>
<li>WS Forms</li>
<li>Mailster Forms</li>
<li>Forminator Forms</li>
</ul>
And more support is being added gradually.

ZeroBounce Email Verification & Validation


I have tested this plugin on several of my personal and business websites, it's awesome. No more spam and fake signups. Service pricing is also decent. Recommended.


Excellent in blocking SPAM


You have a problem with NF form validation. It detects html fields that contains emails (eg mailto links) as email fields and validates those.



if (!empty($value) && is_string($value) && preg_match('/@.+\./', $value) && !str_contains($value, "\n") && !str_contains($value, '\n')) {// rest of the code}



Your approach needs to be changed to:



if (!empty($value) && is_string($value) && preg_match('/@.+\./', $value) && !preg_match('/mailto:/i', $value)) {  $ninjaForm = new Zerobounce_Email_Validator_Form_Public('ninjaforms', $form_data['id']);   // rest of the code}



This should be safer to validate only email addresses (or use a better regex).


Ninja Forms problem

ZeroBounce validates emails on your WordPress site in real-time, blocking invalid and risky emails to improve deliverability and reduce bounce rates.

Email Checker vs ZeroBounce Email Verification & Validation