Troubleshooting & FAQ
Fixes for the things people hit most.
My emails go to spam
Almost always authentication or reputation:
- Verify your domain so SPF + DKIM pass, and add a DMARC record. See
- Send from a subdomain, keep transactional and bulk on separate streams, and
warm up new domains gradually. See Deliverability.
- Check your bounce/complaint rates in Activity. High rates tank placement.
Domain won't verify
DNS records must match exactly. Common causes: the host/name got the domain double-appended, the root needs @, or DNS hasn't propagated yet (wait, then re-verify). See Verify a sending domain.
403 when sending
Two usual reasons: the `from` domain isn't verified, or your account's sending isn't approved yet (new accounts pass an approval step before live sending). Verify the domain and check the approval banner in the dashboard.
401 Unauthorized
The API key is missing, malformed, or revoked. Send it as Authorization: Bearer <key>, and confirm the key belongs to the right project. See API keys.
422 validation error
The response names the bad field. Common ones: from must be Name <address> form, to must be a non-empty array of valid addresses, and you need subject + a body (html/text) unless you use a template.
I sent twice / duplicate emails
Add an idempotencyKey to each send so a retry returns the original result instead of sending again. See Send email via the API.
A recipient isn't getting mail
Check Activity for that message. If it shows suppressed, the address is on your suppression list (a prior bounce, complaint, or unsubscribe). Only remove it if you're sure it's deliverable and wanted.
Webhooks aren't arriving
Confirm the endpoint is public HTTPS and returns 2xx quickly; check recent delivery attempts on the Webhooks page. Handlers must be idempotent. Events can be retried. See Webhooks.
Still stuck?
Email support@mailhuset.com with your project name and, for a specific email, its message id.
Need help? Email support@mailhuset.com.