Description
Super Duper SMTP Mail Bridge replaces the unreliable WordPress PHP mail function with a properly authenticated SMTP connection. Emails reach inboxes instead of spam folders or the void.
🇩🇪🇦🇹🇨🇭 Hinweis für DACH-Nutzer: Plugin und Support sind auf Deutsch (Schweiz/Deutschland/Österreich) verfügbar. Alle Texte und Einstellungen sind vollständig auf Deutsch übersetzt.
Unlike other SMTP plugins, this one gives you everything for free – no feature gates, no “upgrade to Pro” nags, no premium tiers. Every feature listed below works right out of the box.
Why choose this plugin over the big names?
Most popular SMTP plugins either lock essential features behind a paywall or are bloated with dozens of API integrations you don’t need. Here’s what makes Super Duper SMTP Mail Bridge different:
🛡️ Backup SMTP with Automatic Failover — WP Mail SMTP charges $49+/year for this. FluentSMTP and Post SMTP offer fallback, but our implementation automatically logs each failover event separately so you can see exactly when and why your primary server failed.
⏱️ Built-in Rate Limiting — No other free SMTP plugin offers this. Protect your domain reputation when a contact form gets spammed or a plugin goes rogue. Set limits per minute, hour, or day. Blocked emails are logged with a clear “Blocked” status.
🌐 Domain Control (Whitelist & Blacklist) — Block disposable email domains (tempmail.com, guerrillamail.com) or restrict sending to specific recipient domains only. No other free SMTP plugin has both whitelist AND blacklist for recipient domains.
🔐 AES-256-CBC Password Encryption — Your SMTP password is encrypted before it’s stored in the database. Most free SMTP plugins store credentials in plain text or use simple base64 encoding.
📋 Full Email Log with HTML Preview — View the actual rendered email in an iframe preview or switch to source code view. Filter by status (Success, Failed, Blocked, Failover). WP Mail SMTP charges for email logging. We include it free, with content.
🔧 SMTP Debug Transcript — Enable debug mode and get the complete SMTP server conversation logged for each email. Essential for troubleshooting – most plugins don’t offer this at all, or charge for it.
⚠️ Smart Admin Notifications — Get notified by email when failures exceed your threshold. Includes the last error details, recipient, and subject. Built-in loop prevention ensures the notification itself doesn’t trigger more notifications.
👁️ BCC Monitoring & GDPR/DSGVO Compliance — Automatically BCC all outgoing emails to one or more monitoring addresses. Combined with the email log, this provides legally verifiable proof that an email was actually sent – essential for GDPR (DSGVO) compliance. If a data subject ever disputes whether they received a notification, password reset, or consent confirmation, you have both the log entry and an independent BCC copy as evidence. No other free SMTP plugin offers this level of compliance-ready email auditing.
🚫 Zero Bloat — No setup wizards, no upsell banners, no affiliate links to email services, no tracking. Just a clean settings page, your SMTP config, and a log. Under 50 KB total plugin size.
Complete Feature List
- SMTP configuration (host, port, TLS/SSL, authentication)
- Configurable connection timeout (5–120 seconds)
- Custom sender name and email address
- Allowed sender domain validation
- Backup SMTP server with automatic failover
- Rate limiting (per minute, hour, or day)
- BCC monitoring to one or more addresses
- Recipient domain whitelist (only send to these)
- Recipient domain blacklist (never send to these)
- Admin error notification with configurable threshold
- AES-256-CBC password encryption
- Complete email log with status, headers, and error messages
- HTML email preview (rendered) and source code view
- SMTP debug transcript logging
- Test email function directly from admin
- Automatic log cleanup after configurable number of days
- Clean uninstall – removes all data
- Translations: German (CH/DE/AT), English, French, Spanish, Italian, Dutch
Feature Comparison
Feature
Super Duper SMTP
WP Mail SMTP
FluentSMTP
Post SMTP
SMTP Configuration
✅ Free
✅ Free
✅ Free
✅ Free
Email Logging
✅ Free
💰 Pro only
✅ Free
✅ Free
Email Content in Log
✅ Free
💰 Pro only
✅ Free
✅ Free
Backup SMTP Failover
✅ Free
💰 Pro only
✅ Free
✅ Free
Rate Limiting
✅ Free
❌ Not available
❌ Not available
❌ Not available
Domain Whitelist
✅ Free
❌ Not available
❌ Not available
❌ Not available
Domain Blacklist
✅ Free
❌ Not available
❌ Not available
❌ Not available
BCC Monitoring (GDPR compliance)
✅ Free
❌ Not available
❌ Not available
❌ Not available
Password Encryption
✅ AES-256-CBC
❌ Plain/base64
❌ Plain/base64
❌ Plain/base64
SMTP Debug Transcript
✅ Free
❌ Not available
❌ Not available
✅ Free
Admin Error Alerts
✅ Free
💰 Pro only
✅ Free
✅ Free
Sender Domain Validation
✅ Free
❌ Not available
❌ Not available
❌ Not available
Upsell/Ads in Admin
❌ None
⚠️ Yes
❌ None
⚠️ Yes
Screenshots
SMTP server configuration with authentication settings (host, port, TLS/SSL, username, password) 
Sender email settings, backup SMTP server for automatic failover, and rate limiting to protect against spam abuse 
BCC monitoring – sends a copy of every outgoing email to a dedicated address for GDPR-compliant email logging 
Full domain control – whitelist and blacklist for recipient domains, allowed sender domain validation 
Admin error notifications with configurable threshold and complete email logging settings 
Email log overview with status badges (Success, Failed, Blocked, Failover), search, and filter 
Detailed email view showing full content, headers, error messages, and SMTP debug transcript
Installation
- Upload the plugin folder to
/wp-content/plugins/ - Activate the plugin in the WordPress admin
- Go to SMTP Mail Bridge Settings and configure your SMTP server
- Send a test email to verify the configuration
FAQ
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Which SMTP servers are supported?
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Any standard SMTP server works: Gmail, Outlook/Office 365, Mailgun, SendGrid, Amazon SES, Postmark, your own mail server, your hosting provider’s SMTP – if it speaks SMTP, this plugin connects to it.
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Are passwords stored securely?
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Yes. SMTP passwords are encrypted with AES-256-CBC (using OpenSSL) before storage. The encryption key is derived from your WordPress AUTH_KEY salt. Most other SMTP plugins store passwords in plain text or simple base64 encoding.
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What happens when the primary SMTP server fails?
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If you have configured a backup SMTP server, the plugin automatically retries the email through the backup. Both the primary failure and the backup attempt are logged separately, so you have full visibility.
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What is rate limiting and why do I need it?
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Rate limiting caps the number of emails your site can send per minute, hour, or day. This protects you if a contact form gets spammed, a plugin sends mass notifications, or your site is compromised. Emails exceeding the limit are blocked and logged.
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What happens when the plugin is uninstalled?
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All plugin data is completely removed: options, transients, and the custom log database table. No traces left behind.
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Does this plugin work with WooCommerce?
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Yes. All WooCommerce transactional emails (order confirmations, shipping notifications, password resets) are sent through your configured SMTP server.
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Why should I use this instead of WP Mail SMTP or FluentSMTP?
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Rate limiting, domain whitelisting/blacklisting, BCC monitoring with GDPR compliance, sender domain validation, and AES-256 password encryption are features no other free SMTP plugin offers. If you want maximum control over your email delivery without paying for a Pro license, this is your plugin.
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How does BCC monitoring help with GDPR/DSGVO compliance?
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Under GDPR, you may need to prove that a specific email (e.g. a consent confirmation, data deletion notice, or privacy policy update) was actually sent to a user. The email log provides a timestamped record with full content, and the BCC copy gives you an independent second proof stored in a separate mailbox. Together, this creates a verifiable audit trail that can hold up in legal disputes – something no other free SMTP plugin provides out of the box.
Reviews
There are no reviews for this plugin.
Contributors & Developers
“Super Duper SMTP Mail Bridge” is open source software. The following people have contributed to this plugin.
Contributors
“Super Duper SMTP Mail Bridge” has been translated into 1 locale. Thank you to the translators for their contributions.
Translate “Super Duper SMTP Mail Bridge” into your language.
Interested in development?
Browse the code, check out the SVN repository, or subscribe to the development log by RSS.
Changelog
1.2.6 – 11.05.2026
- First public release
- Versions up to 1.2.3 were internal development builds
- SMTP configuration with TLS/SSL, authentication, configurable timeout
- Backup SMTP server with automatic failover on primary failure
- Rate limiting – protection against email abuse (per minute/hour/day)
- BCC monitoring – blind copy of all emails to monitoring address(es)
- Domain control – whitelist and blacklist for recipient domains
- Allowed sender domains validation
- AES-256-CBC password encryption
- Admin error notification when failure threshold is reached
- Debug mode with full SMTP transcript in log
- Complete email log with HTML preview and source code view
- Test email function directly from admin
- Automatic log cleanup after configurable number of days
- Translations: German (CH/DE/AT), English, French, Spanish, Italian, Dutch
- WordPress.org Plugin Check compliant