Q: Why can't I authenticate via SMTP?
Check:
- Using correct SMTP credentials (from
/api/smtp-credentials) - Using STARTTLS on port 587 or 2525
- No firewall blocking outbound SMTP
- Credentials not expired
Q: Why are my API requests failing with 401?
Possible causes:
- Invalid API key (check key is correct and not expired)
- Wrong header (use
X-API-Key: YOUR_KEYfor customer endpoints,Authorization: Bearer YOUR_KEYonly for events API) - Using a key from a different customer account
Q: Why am I getting 429 errors?
You've exceeded the API rate limit (600 requests per minute). Our system returns 429 for high-frequency non-send endpoints (stats, events, etc.).
Note: /api/send and /api/batch accept and queue emails instead of returning 429, unless your account is hard-blocked or quota is exceeded.
Wait for the reset time indicated in the X-RateLimit-Reset header, or reduce your request frequency.
Q: Why aren't my opens/clicks being tracked?
Check:
- Tracking enabled on your account
- HTML email (tracking requires HTML)
- Images enabled in recipient's email client (for opens)
- Privacy features may block tracking (Apple Mail, Gmail)
Q: Why is my email still queued?
Emails may be queued due to:
- IP warm-up limits: Daily sending limits during warm-up
- Domain throttling: Respecting recipient domain rate limits
- Quota exceeded: Monthly limit reached
- Reputation issues: Automatic throttling due to bounces/complaints