email-verification-best-practices
Installation
SKILL.md
Email Verification Best Practices
Email verification checks whether an email address exists, accepts mail, and is safe to send to before you actually send. It's the last gate between your list and your reputation. Every bounced email damages your sender domain reputation. A 5% bounce rate triggers spam filters. A 10% bounce rate can get your domain blacklisted. Verification costs $0.003-0.01 per email. Reputation recovery takes weeks. The math is obvious.
The principle: verify every email before it enters a sequence. No exceptions. Not "most emails." Not "emails from purchased lists." Every email, every time, regardless of source.
How Email Verification Works
The 5-step verification process
Every verification tool runs these checks in order. The result is a composite verdict based on all five.
| Step | What it checks | How | What it catches |
|---|---|---|---|
| 1. Syntax check | Is the format valid? (user@domain.tld) | Regex validation | Typos, malformed addresses, missing @ signs |
| 2. Domain check | Does the domain exist and have mail servers? | DNS MX record lookup | Fake domains, expired domains, typosquatted domains |
| 3. Disposable check | Is this a temporary/throwaway email service? | Match against known disposable domain list | Guerrilla Mail, Temp Mail, Mailinator, 10MinuteMail |
| 4. Role-based check | Is this a shared/role address, not a person? | Pattern matching (info@, sales@, support@, admin@) | Shared inboxes that shouldn't receive personal outbound |
| 5. SMTP verification | Does this specific mailbox exist on the server? | Connects to mail server, simulates delivery without sending | Invalid mailboxes, deactivated accounts, full inboxes |