Email Validator by LifeStep
Validate email syntax and MX, detect disposable/role addresses, suggest typo fixes
No keyCORSHTTPS
SMTPfast
Send transactional email, manage contacts and broadcasts, free 3,000 emails/month
Verified 4 days ago: 100% uptime
API key
Required
HTTPS
Supported
Browser calls
No, needs a proxy
Status
Live · 100/100
What our checks found
- Health score
- 100/100
- Reliability
- 100%
- Average latency
- 665ms
Last checked 2026-09-18. Measured independently, not self-reported by the provider.
How to call it
A starting template for SMTPfast. Replace ENDPOINT with the path from the official documentation, which we link above rather than guess at.
# Requires an API key. Check the docs for whether it goes in a header or a query parameter.
curl -s "https://smtpfa.st/ENDPOINT" \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Accept: application/json"This API does not send CORS headers, so a browser will block a direct call from your front end. Call it from your server, or put a small proxy in front of it.
Where this listing comes from
Aggregated from one public source (public-apis), then normalised and checked by us. If something here is wrong, tell us and we will correct it.
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SMTPfast — common questions
Answered from what our own scheduled checks found, not from the provider's marketing.
Is SMTPfast free to use?
SMTPfast is listed in our free catalogue, but it requires an API key, so you will need to register before your first call. Providers frequently reserve higher limits and commercial use for paid plans.
Does SMTPfast need an API key?
Yes. SMTPfast authenticates with an API key. Keep it server-side rather than in browser code, because anything in your frontend bundle is readable by anyone who opens developer tools.
Can I call SMTPfast from browser JavaScript?
Not directly. SMTPfast did not return CORS headers when we checked, so the browser will block your page from reading the response even though the request itself succeeds. Call it from a server, or put a small proxy in front of it.
Is SMTPfast still working?
Yes, as of 2026-09-18. Our automated check reached SMTPfast and recorded a 100% reliability score with a median response time of 665 ms. We re-check on a schedule, and this page updates with the result.
Is SMTPfast available over HTTPS?
Yes. SMTPfast serves over HTTPS, so you can call it from a secure page without triggering a mixed-content block.