Question 1

What does the Email Existence Checker tool check?

Accepted Answer

The Email Existence Checker checks email addresses across multiple layers: (1) Syntax validation against RFC 5322 format, (2) DNS MX record lookup to confirm the domain can receive email, (3) SMTP handshake to verify the mailbox actually exists, (4) disposable email provider detection to flag throwaway addresses, and (5) role-based address detection (e.g. info@, noreply@). Results are returned in seconds — no sign-up needed.

Question 2

Why should I validate email addresses before sending?

Accepted Answer

Sending to invalid or non-existent email addresses damages your sender reputation, increases hard bounce rates, and can result in your domain being blacklisted by ISPs. Email service providers like SendGrid, Mailchimp, and SES will suspend accounts with bounce rates above 2%. Cleaning your list before sending protects deliverability, reduces costs, and improves open rate accuracy.

Question 3

What is the difference between syntax validation and SMTP verification?

Accepted Answer

Syntax validation checks whether the email address is formatted correctly (e.g. user@domain.com) according to email standards. SMTP verification goes further — it connects to the receiving mail server and simulates sending a message to confirm the specific mailbox exists. SMTP checks are more accurate but some servers use catch-all configurations that accept all addresses, so combining both checks gives the most reliable result.

Question 4

What is a catch-all email address?

Accepted Answer

A catch-all (or accept-all) configuration means the mail server accepts every email addressed to its domain, regardless of whether the specific mailbox exists. For example, anything@example.com might be accepted even if only john@example.com is a real account. Our Catch-All Checker detects this configuration so you know when SMTP verification may produce false positives.

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