SignEmail SMTP & DNS Diagnostic

🚨 Are your WordPress emails going to spam?

Without proper email authentication, services like Gmail, Outlook, and Yahoo may block or mark your emails as spam. This results in lost notifications, password resets, and order emails.

SignEmail SMTP helps you send reliable WordPress emails using professional SMTP servers, with optional DKIM authentication support.

Why email authentication matters

Modern email providers require proper authentication (SPF, DKIM, DMARC) to trust your messages. Without it, even valid emails may be filtered as spam.

📬 SMTP Email Delivery

Send all WordPress emails through reliable SMTP servers instead of PHP mail(), improving deliverability and consistency.

⚙️ Universal SMTP Compatibility

Compatible with Gmail, Outlook, Brevo, cPanel, OVH, Infomaniak, SiteGround, GoDaddy, Bluehost, WP Engine, Kinsta, Namecheap, Gandi, o2switch, LWS, and more.

🔍 Email Testing Tool

Send test emails to verify inbox delivery and diagnose spam placement in real conditions.

🔎 DNS Diagnostic Tool

Check SPF, DKIM, and DMARC records using Cloudflare DNS-over-HTTPS.

🔒 Secure Storage

SMTP credentials are encrypted using AES-256-CBC and stored securely in your WordPress database.

🌐 Multilingual Support

Full French and English interface with per-user language selection.

SMTP Features

• Full SMTP configuration (SSL / TLS / STARTTLS / None)
• Encrypted password storage (AES-256-CBC)
• Force sender email and name
• Debug logging system
• Built-in email test tool
• DNS verification (SPF / DKIM / DMARC)
• Compatible with WooCommerce, CF7, Elementor, Gravity Forms, BuddyPress, LearnDash, etc.
• Fully intercepts wp_mail()

Optional DKIM Support

DKIM email signing is available in the Premium version of this plugin — smtp-dkim.com.

• Works alongside SMTP delivery
• Improves inbox trust and deliverability

Security & Privacy

• SMTP credentials encrypted before storage
• No credentials are sent to external servers
• License verification (if used) only transmits license key + domain name
• No email content is ever transmitted externally

External Services

This plugin connects to the following external services:

1. Cloudflare DNS-over-HTTPS

Used by the DNS Diagnostic tool to check SPF, DKIM, and DMARC records.

• Service: Cloudflare DNS-over-HTTPS API
• Endpoint: https://cloudflare-dns.com/dns-query
• Data sent: Domain name and DKIM selector (no personal data)
• When: Only when the admin manually runs the DNS diagnostic tool
• Terms of Service: https://www.cloudflare.com/terms/
• Privacy Policy: https://www.cloudflare.com/privacypolicy/

2. User-configured SMTP server

Used to deliver WordPress emails via the SMTP protocol.

• Service: Any SMTP server configured by the site administrator (e.g. Gmail, Outlook, Brevo, cPanel)
• Data sent: Email content as configured by WordPress (wp_mail)
• When: Every time WordPress sends an email
• Terms of Service and Privacy Policy: Refer to your SMTP provider

3. smtp-dkim.com — License validation (Premium version only)

The Premium version validates the license key to enable DKIM signing.

• Endpoint: https://smtp-dkim.com/wp-json/sdlm/v1/validate
• Data sent: License key + domain name only — no email content, no SMTP credentials
• When: On plugin activation and periodically in the background
• Terms of Service: https://smtp-dkim.com/politique-de-confidentialite/
• Privacy Policy: https://smtp-dkim.com/politique-de-confidentialite/

Note: The free version available on WordPress.org does not include license validation or DKIM signing.