What Is Email Verification?
Email verification is the process of confirming that an email address exists, is properly formatted, and can receive mail. It works by connecting to the recipient's mail server via SMTP and checking whether the specific mailbox is active, without actually sending an email. Verification catches invalid addresses, disposable emails, and catch-all domains before you send, protecting your sender reputation and keeping bounce rates under 2%.
How does email verification work?
Email verification uses a multi-step process. First, syntax validation checks the format (text@domain.extension). Second, domain verification confirms the domain exists and has MX (mail exchange) records. Third, SMTP verification connects to the mail server and asks if the specific mailbox exists. The server responds with a status code: 250 OK means the mailbox exists, 550 means it does not. Fourth, additional checks detect catch-all domains (servers that accept all addresses), disposable email services, and known spam traps. The entire process takes 1-5 seconds per address.
What is the difference between email verification and email validation?
Email validation checks format only: does the address look like a real email? It catches typos like 'john@gmial.com' or missing @ symbols. Email verification checks existence: does the mailbox actually work? It catches former employees, fake addresses, and disabled accounts. Validation catches about 10% of bad addresses. Verification catches about 95%. For campaign sends, you need verification. For form fields, validation provides immediate feedback.
Why does email verification matter for deliverability?
Email providers (Google, Microsoft, Yahoo) track your bounce behavior. High bounce rates signal that you send to unverified lists. A single campaign with 5% bounces lowers your sender score. Over weeks of poor hygiene, the effect compounds until emails land in spam. The industry threshold is 2% bounce rate. Above that, reputation damage begins. Above 5%, most providers throttle your sends. Recovery takes 30-60 days of clean sending. Real-time verification prevents this entirely.
What are typical email verification accuracy benchmarks?
Verification accuracy by list hygiene frequency: daily verification achieves 0.3% bounce rate and 95% inbox placement. Weekly: 0.8% bounce rate, 92% inbox placement. Monthly: 1.5% bounce rate, 87% inbox placement. Quarterly: 2.8% bounce rate, 81% inbox placement. Never cleaned: 6.5%+ bounce rate, 68% inbox placement. The difference between daily and never is 27 percentage points of inbox placement, translating directly to pipeline and revenue.
Frequently Asked Questions
How accurate is email verification?
SMTP verification catches approximately 95% of invalid addresses. The remaining 5% are typically catch-all domains where the server accepts all addresses but may silently discard invalid ones. Good verification tools flag catch-all addresses as risky so you can make informed decisions.
Can email verification damage my sender reputation?
No. Verification connects to mail servers but does not actually send emails. It asks if a mailbox exists and disconnects. There is no message content, no spam risk, and no impact on your sending domain.
How often should I verify my email list?
Before every major campaign, and at least quarterly for your full database. B2B email addresses decay at 25-30% per year. For high-volume outbound teams, monthly or continuous verification is recommended.
What is a catch-all domain?
A catch-all domain is configured to accept emails sent to any address at that domain, even if the specific mailbox does not exist. The email may be delivered to a default inbox, silently discarded, or bounced later. Verification flags these as risky because deliverability is uncertain.