If you’re running email campaigns, cleaning lists, or just trying to keep your database tidy, you’ve probably run into headaches with email verification tools. Usebouncer is one of the better-known options out there, but even good tools hit snags now and then. If your Usebouncer verification isn’t working how you expect, this guide is for you. I’ll walk you through real fixes for the most common problems—no fluff or hand-waving.
1. Double-Check the Obvious: API Keys, Endpoints, and Input
You’d be surprised how often the basics trip people up. Before you start digging for obscure bugs, check these first:
- API Key: Make sure you’re using an active API key. Expired or revoked keys are a top culprit.
- Endpoint URLs: Are you hitting the right endpoint? Usebouncer has different URLs for single vs. bulk verification. Mixing them up leads to errors.
- Input Formatting: Garbage in, garbage out. If you’re sending malformed email addresses, don’t expect magic. Usebouncer expects clean, RFC-compliant emails.
Pro tip: Test a few known-good addresses manually via the dashboard or a simple curl call. If those work but your integration fails, the problem’s probably in your code, not Usebouncer.
2. Interpreting Error Messages (And When They’re Useless)
Usebouncer generally returns clear error messages, but sometimes they’re… less than enlightening.
- 401 Unauthorized or 403 Forbidden: Your API key’s wrong or you don’t have access. Double-check your credentials.
- 422 Unprocessable Entity: Usually bad input (malformed email, missing field, etc.).
- 429 Too Many Requests: You’ve hit rate limits (more on that below).
- 500/502/503 Errors: Server-side issues. Sometimes Usebouncer has real downtime, but often these are transient—wait and try again.
What to do when the error makes no sense:
If you’re getting a vague or unexpected error, strip your request down to bare bones and test with a single, simple email.
Still broken?
- Check Usebouncer’s documentation for any recent API changes.
- Hit their status page for outages.
- Try a different network—sometimes firewalls or proxies mess with outgoing requests.
3. Rate Limits and Throttling
If you’re verifying a big batch of emails, Usebouncer will slow you down (or block you) if you go too fast. Here’s how to stay on their good side:
- Understand your plan’s limits. Free and lower-tier plans have strict caps on requests per second and daily volume.
- Watch for 429 errors. These mean “slow down.” Back off and retry after a few seconds.
- Batch requests sensibly. Don’t slam the API with hundreds at once. Space them out, and consider exponential backoff for retries.
What not to do:
Don’t try to “game” the system by using multiple keys or fake accounts. They’ll catch on, and you’ll lose access.
4. False Positives, “Unknown” Results, and Other Accuracy Headaches
No email verifier is perfect, and Usebouncer is no exception. Sometimes you’ll get “unknown” or “accept all” results, or false positives/negatives. Here’s what’s going on:
- Catch-all domains: Some mail servers accept any email address, legit or not. Usebouncer will call these “accept all” or “unknown.” There’s no reliable way to test these—don’t trust anyone who says otherwise.
- Disposable/temporary emails: These get flagged, but new disposable providers pop up daily. Don’t expect 100% coverage.
- Graylisting and temporary failures: Some mail servers temporarily reject requests from verifiers. These cause “unknown” results. Try again later, but don’t hammer the API.
Best practice:
Treat “unknown” and “accept all” as a gray area. If you’re sending cold emails, probably best to skip these addresses. If it’s a newsletter, you might take the risk.
5. Bulk Verification Gotchas
Uploading a CSV or verifying in bulk? A few common pain points:
- File format: Stick to plain CSV, UTF-8 encoding, and ensure you have a header row labeled “email.” Anything else, and you risk silent failures or weird results.
- File size limits: Usebouncer puts a cap on bulk upload file size. If you hit a wall, split your list.
- Processing delays: Large uploads can take a while, especially at peak times. Don’t expect instant results.
What to ignore:
Don’t waste time looking for advanced “settings” to speed up processing—there aren’t any magic switches hidden in the UI.
6. Integration Issues (Zapier, CRMs, Marketing Tools)
Connecting Usebouncer to other tools sometimes goes sideways:
- Zapier: Make sure your Zap is getting the right data from the trigger app. Most failures are from mismatched fields, not Usebouncer itself.
- CRMs/Email platforms: If you’re seeing sync failures, check for:
- Field mismatches (e.g., wrong column names)
- Permissions (does Usebouncer have access to update records?)
- API limits on the CRM side
When in doubt, test with a tiny data set and watch logs closely.
7. Results Don’t Match Your Expectations
Maybe you’re seeing more invalids than you thought, or Usebouncer says an address is “valid” but it still bounces. Here’s the reality check:
- No tool can catch everything. Some addresses pass syntax and server checks, but still won’t deliver. That’s email for you.
- Data decay is real. Lists go stale fast. Even if your list was clean last month, expect churn.
- “Valid” ≠ Guaranteed Delivery. Usebouncer can’t force a recipient to accept your message. It just checks if the address should work.
What works:
Usebouncer is solid for clearing obviously bad addresses, catching typos, and flagging most disposable emails. Don’t expect perfection.
8. When All Else Fails: Contact Support (But Come Prepared)
Sometimes it really is a bug or a backend issue. Before you file a ticket:
- Collect error messages, timestamps, and sample payloads.
- Give them minimal, reproducible examples (e.g., “this email always fails, here’s the request”).
- Don’t just say “it doesn’t work.” The more details, the faster you’ll get real help.
Their support is generally responsive, but like any SaaS, they’ll be a lot faster if you help them help you.
Keep It Simple and Iterate
Email verification isn’t magic, and even a solid tool like Usebouncer has rough edges. Don’t get bogged down chasing perfection or blaming your tools for the realities of email deliverability. Start with the basics, automate what you can, and check your assumptions before you panic. Tidy up your process step by step, and you’ll avoid most headaches before they start.