Question 1

How can I check if an email address is valid without sending an email?

Accepted Answer

CheckEmailNow verifies if an email exists using a 4-step protocol: RFC 5322 syntax compliance, live DNS MX record lookup via Google DNS-over-HTTPS, disposable domain filtering against 4,000+ temporary providers, and an in-browser simulated SMTP handshake probe (RCPT TO). The connection is severed before sending any DATA command, ensuring the recipient never receives an email or notification.

Question 2

Why is client-side (in-browser) email verification safer for GDPR & CCPA compliance?

Accepted Answer

Traditional email validation services upload your contact lists to third-party cloud servers, creating legal data processing risks under GDPR and CCPA. CheckEmailNow executes all checks directly in your browser's memory using client-side DNS-over-HTTPS. Your proprietary contact lists and customer emails are never uploaded, stored, or processed on external servers.

Question 3

What is a Catch-All email domain and why can't basic email checkers verify it?

Accepted Answer

A Catch-All (accept-all) mail server is configured to return a 250 OK status for any address at that domain, even if the mailbox does not exist. Basic validators misclassify these as valid. CheckEmailNow detects wildcard accept-all behavior and flags it as Risky, helping you isolate these contacts into low-volume nurture drips to avoid delayed bounces.

Question 4

How accurate is an online email validator on Gmail, Outlook, and Yahoo addresses?

Accepted Answer

CheckEmailNow delivers 99%+ verification accuracy across major consumer and enterprise email providers, including Google Workspace (Gmail), Microsoft 365 (Outlook/Hotmail), Apple iCloud, Proton Mail, and Zoho. For Yahoo and strict corporate servers with anti-probing firewalls, our engine evaluates MX priority, SPF, DMARC, and simulated response patterns.

Question 5

How often should I validate my email marketing list, and can I check emails in bulk?

Accepted Answer

Email databases decay at approximately 22% per year due to employee turnover, domain expirations, and abandoned inboxes. You should validate real-time at form submission and run bulk list cleaning every 14 to 30 days before major campaign sends. CheckEmailNow includes a free Bulk Verifier that processes CSV, TXT, and TSV spreadsheets directly in your browser.

Question 6

What is an SMTP handshake probe (RCPT TO) and is it safe?

Accepted Answer

An SMTP handshake probe connects directly to the target mail server's Mail Exchanger (MX) IP and issues an RCPT TO command to query mailbox existence. CheckEmailNow immediately disconnects before sending any DATA command, making the probe 100% non-intrusive and silent so the recipient is never notified.

Question 7

How do disposable email detectors block 4,000+ burner domains?

Accepted Answer

CheckEmailNow maintains an up-to-date blocklist of over 4,000 temporary and disposable email providers (such as Mailinator, YOPmail, and Guerrilla Mail). When an email is checked, the domain is instantly matched against this blocklist to prevent fake registrations and spam trap poisoning.

Question 8

What are DNS-over-HTTPS (DoH) queries and why are they used for MX lookups?

Accepted Answer

DNS-over-HTTPS (DoH) performs encrypted DNS resolution over HTTPS protocols (RFC 8484). It bypasses local ISP interference, prevents DNS tampering, and allows secure, lightning-fast Mail Exchanger (MX) record queries directly from the user's browser.

Question 9

How do I reduce hard and soft bounce rates in email marketing?

Accepted Answer

To reduce bounce rates below 1%, remove invalid syntax, block disposable burner emails, verify MX records before sending, flag catch-all mailboxes, and maintain proper SPF, DKIM, and DMARC authentication records.

Question 10

Can I verify email lists in bulk for free without uploading my data to a server?

Accepted Answer

Yes. CheckEmailNow features a free Bulk Verifier tool that allows you to upload CSV, TXT, or TSV spreadsheets. All records are processed locally in your browser memory via DoH and SMTP probing, ensuring complete privacy with zero cloud server storage.