Test Your SMTP Credentials in Seconds

SMTP Test Tool is a fast, secure diagnostic tool that helps developers verify their SMTP server configuration. Test connection, authentication, and email delivery with real-time step-by-step results—no more guessing why your emails aren't sending.

One-Click Provider Setup

Get started instantly with preset configurations for major providers:

• Gmail - Auto-configured with App Password guidance
• Outlook / Microsoft 365 - Office 365 SMTP settings
• Yahoo Mail - Pre-filled with correct host and port
• SendGrid - API key authentication setup
• Mailgun - Domain-specific SMTP credentials
• Amazon SES - Regional endpoint configuration
• Zoho Mail - Direct SMTP settings
• iCloud - App-Specific Password instructions

Click a provider, fill in your credentials, and test.

3-Step Real-Time Diagnostics

Watch your SMTP test progress through three clear phases:

1. Connection - Establishes TCP connection to the SMTP server
2. Authentication - Verifies your username and password
3. Delivery - Sends the test email and confirms acceptance

Each step shows its status (passed/failed) with precise timing in milliseconds.

Two Testing Modes

Choose the right test for your needs:

• Send Test Email - Full test: connect, authenticate, and send a real email
• Verify Connection Only - Quick check: connect and authenticate without sending

Perfect for when you just need to confirm your credentials work.

Human-Friendly Error Messages

No more cryptic SMTP error codes. When something fails, get clear explanations:

• "Authentication failed. Check your username and password. Some providers require app-specific passwords."
• "Connection refused. Check the SMTP host and port are correct."
• "The server requires STARTTLS encryption. Change your encryption setting to STARTTLS."

13 error patterns mapped to actionable guidance.

Security by Design

Your credentials are safe:

• Never stored - Credentials are used for the single test request only
• Never logged - No server-side logging of passwords or usernames
• Rate limited - 10 requests per minute per IP to prevent abuse
• Input validated - All fields validated with Zod before any SMTP operation
• Single recipient - No CC, BCC, or bulk sending

Copy Results as JSON

Export your test results with one click for documentation or debugging:

• Step-by-step status with timing
• Message ID for delivery tracking
• Total duration
• Error details if applicable

Developer-Friendly Stack

Built with modern tools:

• Next.js 16 with App Router
• TypeScript for type safety
• Nodemailer for SMTP operations
• shadcn/ui + Framer Motion for UI
• Tailwind CSS for styling
• Dark/Light Mode support

Use Cases

Perfect for:

• Setting up transactional email - Verify SMTP credentials before integrating
• Debugging delivery issues - Pinpoint where the connection fails
• Onboarding new providers - Quick validation of SendGrid, Mailgun, SES credentials
• CI/CD pipeline checks - Confirm SMTP access from different environments
• Client handoffs - Verify credentials clients provide are working