Troubleshooting

This guide helps you resolve common issues when using Mailloop.

Emails Not Appearing

If emails aren't showing up in your inbox, try these steps:

Check SMTP Configuration

Verify your SMTP settings are correct:

{
  host: 'smtp.mailloop.io',  // Correct hostname
  port: 587,                 // Or 465 for SSL
  auth: {
    user: 'your-username',   // Sandbox username
    pass: 'your-password'    // Sandbox password
  }
}

Verify Credentials

1. Go to your sandbox settings
2. Check your username and password
3. Try resetting your password if needed

Check Application Logs

Look for SMTP errors in your application logs:

• Authentication failures
• Connection timeouts
• TLS/SSL errors

Test with CLI

Verify your credentials work using curl:

curl --url 'smtp://smtp.mailloop.io:587' \
  --ssl-reqd \
  --mail-from 'test@example.com' \
  --mail-rcpt 'test@mailloop.io' \
  --user 'username:password' \
  -T message.txt

Authentication Errors

Error: "535 Authentication failed"

Solutions:

1. Verify username and password are correct
2. Check for extra spaces in credentials
3. Ensure you're using the sandbox username, not your email
4. Try resetting your sandbox password

Connection Issues

Error: "Connection timeout" or "Could not connect to SMTP host"

Solutions:

Check Firewall

Ensure your firewall allows outbound connections:

• Port 587 (STARTTLS)
• Port 465 (SSL/TLS)

Test Connectivity

telnet smtp.mailloop.io 587

If this fails, your network may be blocking the connection.

Try Alternative Port

If port 587 is blocked, try port 465 with SSL:

{
  host: 'smtp.mailloop.io',
  port: 465,
  secure: true,  // Use SSL
  auth: { ... }
}

TLS/SSL Errors

Error: "SSL routines" or "certificate verify failed"

Solutions:

Update Libraries

Ensure your SMTP library is up to date:

npm update nodemailer  # Node.js
pip install --upgrade python-smtplib  # Python

Disable Certificate Verification (Development Only)

Warning: Only for local development, never in production.

{
  host: 'smtp.mailloop.io',
  port: 587,
  tls: {
    rejectUnauthorized: false  // Disable for testing only
  }
}

Emails Missing Content

If emails appear empty or malformed:

Check Email Format

Ensure you're setting both text and HTML:

{
  text: 'Plain text version',
  html: '<p>HTML version</p>'
}

Verify Character Encoding

Use UTF-8 encoding for international characters:

msg = MIMEText(text, 'plain', 'utf-8')

Check Content-Type Headers

Ensure proper MIME types are set for HTML emails.

Performance Issues

If emails are slow to appear:

Check Sandbox Status

Verify your sandbox is active:

1. Go to sandbox settings
2. Ensure "Active" status is enabled

Review Rate Limits

Check if you've exceeded rate limits:

• Free plan: 100 emails/hour
• Pro plan: 1,000 emails/hour

Clear Browser Cache

Sometimes the UI needs a refresh:

1. Hard reload the page (Cmd+Shift+R or Ctrl+Shift+R)
2. Clear browser cache
3. Try a different browser

API Issues

Rate Limiting

Error: "429 Too Many Requests"

Solution: Wait for the rate limit reset time indicated in headers.

Invalid API Key

Error: "401 Unauthorized"

Solutions:

1. Verify API key is correct
2. Check if key has been revoked
3. Generate a new API key if needed

Still Having Issues?

If you're still experiencing problems:

1. Check Status Page: Visit status.mailloop.io for service status
2. Contact Support: Submit a ticket through the Help & Support page
3. Community Forum: Search or ask in the Mailloop community

When reporting issues, include:

• Error messages
• SMTP configuration (without passwords)
• Application logs
• Steps to reproduce the problem