Description
Email Checker for Contact Form 7 validates email addresses in real time using the Emails Checker API before accepting form submissions. This stops spam, promotional emails, and invalid contacts from reaching your inbox.
The plugin performs comprehensive email verification including:
- DNS validation, including MX record lookup
- Disposable email address detection in real time
- Misspelled domain detection
- Email syntax verification (IETF/RFC standard conformance)
- Mailbox existence checking
- Catch-all testing
- Greylisting detection
- SMTP connection and availability checking
The plugin integrates seamlessly with Contact Form 7 — no form changes required. Simply enter your API key in the settings page and the plugin automatically validates all email fields.
Privacy
This plugin uses WordPress transients to store rate-limiting counters keyed by the visitor’s IP address (hashed with MD5). No email addresses or personal data are sent to the Emails Checker API — only the email field value being validated is transmitted. Rate-limit transients expire automatically within the configured time window (default 60 seconds).
The plugin integrates with WordPress’s built-in privacy tools:
* Data export: IP-based rate-limit data associated with a given email address is included in WordPress privacy exports.
* Data erasure: Rate-limit transients can be erased via WordPress privacy erasure requests.
Screenshots
Installation
Manual Installation
- Upload the
email-checker-for-contact-form-7folder to the/wp-content/plugins/directory. - Activate the Email Checker for Contact Form 7 plugin through the ‘Plugins’ menu in WordPress.
- Navigate to Settings > Emails Checker for CF7 to configure the plugin.
- Sign up for a free API key at app.emails-checker.net.
- Paste your API key into the settings page and save.
FAQ
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How many emails can I check?
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Our Free Plan gives you 100 SMTP credits per month for SMTP status checks. Basic syntax checking is done locally for free. If you have more than 100 contact form submissions per month, check out our affordable pricing at emails-checker.net/pricing.
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Do I have to make changes to my form?
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No. The plugin works automatically with all Contact Form 7 forms. Just enter your API key and you’re done.
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What if I run out of credits?
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If you run out of credits, the plugin will stop performing SMTP checks. Your contact form functionality will continue to work — emails will pass through basic syntax validation only.
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Is the API key secure?
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Yes. The API key is stored securely in the WordPress options table and is masked in the settings page. Only users with ‘manage_options’ capability can view or modify it.
Reviews
Contributors & Developers
“Email Checker for Contact Form 7” is open source software. The following people have contributed to this plugin.
Contributors
“Email Checker for Contact Form 7” has been translated into 2 locales. Thank you to the translators for their contributions.
Translate “Email Checker for Contact Form 7” into your language.
Interested in development?
Browse the code, check out the SVN repository, or subscribe to the development log by RSS.
Changelog
3.1
- Version bump to 3.1 with full backward compatibility to PHP 7.2
- Confirmed tested compatibility up to WordPress 7.0.3
- Added per-IP rate limiting to prevent abuse from bots with invalid API keys
- Added automatic API key blacklist with configurable cooldown when auth errors (HTTP 401/403) are detected
- Admin users with manage_options can bypass rate limiting for status checks on the settings page
- Rate limit transients are automatically cleared when settings are saved
- Fixed transient cleanup query to correctly clear all rate-limit and blacklist data
- Fixed error message propagation: specific errors (rate limit, invalid API key) are now displayed to users in form validation messages
- Added GDPR compliance: WordPress privacy data export and erasure support for IP-based transients
- Added privacy policy section to readme
- Added admin setting to control whether specific API error messages or generic messages are shown to end users
- Added admin notice and settings UI for rate limit configuration
- Added “Clear Block Now” button to manually reset blacklisted API keys
- Fixed “Clear Block Now” not working: admin status check on the settings page was immediately re-blacklisting the API key after it was cleared. Admin status checks no longer trigger blacklist when the API returns 401/403.
- Updated user-agent string for API requests
- Minor documentation and inline comment improvements
3.0.0
- Complete rewrite with MVC architecture
- WordPress Settings API integration for proper settings management
- REST API endpoints for external integrations
- AJAX support for async email verification
- Caching layer to reduce API calls and respect rate limits
- Improved security: nonces, capability checks, input sanitization, output escaping
- Proper internationalization support
- PHP 7.2+ minimum requirement
- WordPress 5.0+ minimum requirement
2.5
- Updated for newer WordPress version 6.6
- Improved contact form email field detection and validation
2.4
- Updated for newer WordPress version 6.4.2
- Fixed minor issues
2.3
- Updated for newer WordPress version 6.1.1
- Added option to allow specific email types
- Added option to block emails if out of credits
- Added more email catching abilities
2.2
- Minor updates
2.1
- API Updates
- Minor CSS and form security improved
2.0
- Added newer version of Emails Checker API
- api.emails-checker.net
- New block emails on errors option
1.2
- Fixed minor field issues
1.1
- Connectivity issue fixed
- Added more security factors
1.0
- Initial release