📡What is an SMTP ping?
An SMTP ping is a technical method used to check if an email address is valid without sending an actual email.
It connects to the recipient's mail server and simulates the first steps of email delivery (via the SMTP protocol) to see if the server accepts the address.
⚙️How does SMTP ping work?
Here's the basic flow:
Your tool (e.g. Lero) connects to the recipient's MX server
It starts an SMTP conversation:
- Introduces itself
- Announces the sender
- Issues a RCPT TO command with the target email
The server replies with a status:
address likely exists
invalid
risky
⚠️ Importantly: no actual message is sent.
🎯Why is SMTP ping used?
SMTP ping is the core of high-accuracy email validation.
It helps:
- Detect invalid or fake inboxes
- Filter out typos and misspelled domains
- Flag temporary or catch-all setups
- Improve your sender score and deliverability
🚫Can SMTP ping be blocked?
Yes. Some mail servers:
- Use greylisting (temporarily reject unknown senders)
- Block validation attempts to stop scrapers
- Respond "OK" even for invalid inboxes (catch-all)
That's why tools like Lero combine SMTP ping with additional logic to detect false positives and retries.
📌 Summary
An SMTP ping is a crucial technique for email validation that simulates email delivery without actually sending messages. It's the foundation of accurate email verification and helps protect your sender reputation.
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