shawfactor

mattsenate

This plugin is can be used for petitions, events, or any verified list and as far as I know is unique in WordPress.
Creating a petition/list/signup is as easy as adding a shortcode to a post or page (or CPT). From there additional editors are available to configure easch aspect of the sign up. Everything is completely self hosted and all list members become users of your site (not a third parties).
Available shortcodes:
[lh_signing_form] (enable signatories on any post, page, or custom post type)
Unconfirmed signatories: [lh_signing_unconfirmed_count]
Confirmed signatories: [lh_signing_confirmed_count]
Total signatories: [lh_signing_total_count]
[lh_signing_unconfirmed_list] (unformated list)
[lh_signing_confirmed_list] (unformated list)
You can customise the display of the signing form ([lh_signing_form]) via a number of shortcode arguments more information is available <a href="https://lhero.org/portfolio/lh-signing/" title="Additional Plugin documentation" rel="nofollow ugc">here</a>

LH Signing

LH Signing allows you to create configurable validated lists like petitions or event sign ups. It is the only self hosted solution in WP

clearoutio

Clearout Email Validation plugin seamlessly integrates with all major forms to validate the email addresses in real time.
The plugin performs 20+ refined real-time validation checks to determine the current status of the email address. These checks include extensive verifications like greylist verification, anti-spam check, gibberish check, catch-all verification, email blacklist verification, temporary email address check, and more.
<h4>Key Benefits of Using Clearout Email Verification Plugin:</h4>
<ul>
<li>Accept only safe-to-send email address to protect your sender reputation</li>
<li>Accept only business or work email addresses</li>
<li>Prevent fraudulent signups or leads getting into CRM by stopping <a href="https://clearout.io/blog/2020/09/30/dont-let-your-email-campaigns-be-a-victim-of-disposable-email-addresses" rel="nofollow ugc">temporary / disposable / throw away email addresses</a></li>
<li>Customization to Block free email address providers like gmail.com / yahoo.com / hotmail.com</li>
<li>Remove duplicate and alias email addresses</li>
</ul>
<h4>How to Install Clearout Email Verifier Plugin</h4>
Obtain an API Token: 
1. Log in to your Clearout account. 
2. Navigate to the <a href="https://app.clearout.io/developer/api/list" rel="nofollow ugc">‘Developer’</a> menu and click on ‘+ Create API Token’. 
3. Add the necessary details for reference, and click on “Create” to generate the API token.
Create a Clearout Account (if you don’t have one): 
1. <a href="https://app.clearout.io/register" rel="nofollow ugc">Sign up</a> for a Clearout account to get 100 free email validation credits with no credit card required.
For more detailed instructions, visit Clearout <a href="https://clearout.io/integrations/wordpress/" rel="nofollow ugc">Email Verifier Plugin Installation</a>.
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/YG5BrBn7FHo?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>
<h4>Supported Forms/Plugins</h4>
The Clearout email verification plugin supports a rich set of popular form-based plugins by listening to email address capture flow or by hooking into WordPress is_email() function:
<ul>
<li>Elementor Form</li>
<li>Gravity Forms</li>
<li>Forminator Form</li>
<li>WooCommerce Checkout Forms</li>
<li>WooCommerce Registration Form</li>
<li>Fluent Form</li>
<li>WP Forms</li>
<li>Formidable forms</li>
<li>WS Form </li>
<li>WP-Members</li>
<li>Contact Form</li>
<li>Mailster Form</li>
<li>MailChimp</li>
<li>Ninja Forms</li>
<li>Profile Builder</li>
<li>Ultimate Member registration form</li>
<li>Users Ultra registration form</li>
<li>JetPack comments and a contact form</li>
<li>MailPoet</li>
<li>Theme My Login</li>
<li>Paid Memberships Pro</li>
<li>Form Maker by 10Web</li>
<li>Visual Form Builder</li>
<li>Any WordPress registrations & contact forms </li>
</ul>
<h4>Key Features</h4>
<ul>
<li>Accurate Email Verification</li>
<li>Fastest Real-time Email Validation</li>
<li>Seamless API Integration</li>
<li>Guaranteed Deliverability (Safe to send)</li>
<li>High Precision Advanced Catch-all Resolver</li>
<li>Block Role Email</li>
<li>Block Disposable Email</li>
<li>Block Gibberish Email</li>
<li>Email / Domain Allowlisting and Blocklisting</li>
<li>Custom Error Message</li>
<li>Limit email validation to only required pages</li>
<li>Low Credit Notification Alert</li>
<li>Team Accounts</li>
<li>Syntax Verification</li>
<li><a href="https://docs.clearout.io/api-overview.html#testing" rel="nofollow ugc">Test email addresses</a></li>
</ul>
<h4>Know A Little More About Clearout Email Verification Service</h4>
In addition to its availability as a WordPress Plugin, Clearout Email Verifier supports email verification in multiple forms and ways to meet the needs of the user. Other verification methods supported by Clearout Email Verifier are – Bulk email list validation, real-time email validation API, and Form Guard Email Validation.
<h4>FURTHER READING</h4>
More about Clearout Email Verification
<ul>
<li><a href="https://clearout.io/email-verification-api/" rel="nofollow ugc">https://clearout.io/email-verification-api/</a></li>
<li><a href="https://clearout.io/disposable-email-checker/" rel="nofollow ugc">https://clearout.io/disposable-email-checker/</a></li>
<li><a href="https://clearout.io/integrations/" rel="nofollow ugc">https://clearout.io/integrations/</a></li>
<li><a href="https://clearout.io/help/" rel="nofollow ugc">https://clearout.io/help/</a></li>
<li><a href="https://docs.clearout.io/" rel="nofollow ugc">https://docs.clearout.io/</a></li>
</ul>
Other Clearout Services
<ul>
<li><a href="https://clearout.io/email-finder/" rel="nofollow ugc">https://clearout.io/email-finder/</a></li>
<li><a href="https://clearout.io/sales-prospecting/chrome-extension/" rel="nofollow ugc">https://clearout.io/sales-prospecting/chrome-extension/</a></li>
<li><a href="https://clearout.io/sales-prospecting/advanced-data-enrichment/" rel="nofollow ugc">https://clearout.io/sales-prospecting/advanced-data-enrichment/</a></li>
<li><a href="https://clearout.io/reverse-lookup/linkedin/" rel="nofollow ugc">https://clearout.io/reverse-lookup/linkedin/</a></li>
<li><a href="https://clearout.io/reverse-lookup/email/" rel="nofollow ugc">https://clearout.io/reverse-lookup/email/</a></li>
</ul>

Clearout Email Validator – Real-Time Email Verification on WordPress Forms

Block invalid emails like temporary, disposable, etc. with our real-time email verification. Verify email address during form-fill and stop form spam.

LH Signing vs Clearout Email Validator – Real-Time Email Verification on WordPress Forms