How It Works

EmailVerify uses a multi-layer verification approach to accurately determine email deliverability. Each email goes through several validation stages to provide the most accurate results possible.

Verification Process

Email Submitted
      ↓
┌─────────────────┐
│ 1. Syntax Check │ → Invalid format? → Return invalid
└────────┬────────┘
         ↓
┌─────────────────┐
│ 2. Domain Check │ → Domain doesn't exist? → Return invalid
└────────┬────────┘
         ↓
┌─────────────────┐
│ 3. MX Record    │ → No mail server? → Return invalid
│    Verification │
└────────┬────────┘
         ↓
┌─────────────────┐
│ 4. Disposable   │ → Matches database? → Flag as disposable
│    Detection    │
└────────┬────────┘
         ↓
┌─────────────────┐
│ 5. SMTP Check   │ → Mailbox doesn't exist? → Return invalid
│    (Optional)   │
└────────┬────────┘
         ↓
┌─────────────────┐
│ 6. Score        │ → Calculate confidence score
│    Calculation  │
└────────┬────────┘
         ↓
    Return Result

Verification Stages Explained

Stage 1: Syntax Validation

We first check if the email address follows valid RFC 5322 format rules:

• Contains exactly one @ symbol
• Local part (before @) follows naming rules
• Domain part (after @) is properly formatted
• No invalid characters present

Examples:

• user@example.com - Valid syntax
• user.name+tag@example.co.uk - Valid syntax
• user@ - Invalid (missing domain)
• @example.com - Invalid (missing local part)

Stage 2: Domain Verification

We verify that the domain actually exists and is properly configured:

• DNS lookup for the domain
• Check domain registration status
• Verify domain is not on blocklists

Stage 3: MX Record Check

We query DNS for the domain's MX (Mail Exchange) records to confirm it can receive email:

example.com → MX: mail.example.com (Priority: 10)
            → MX: backup.example.com (Priority: 20)

Domains without MX records cannot receive email.

Stage 4: Disposable Email Detection

We maintain a database of 5000+ known disposable email domains, including:

• Public disposable services (Mailinator, 10MinuteMail, etc.)
• Private disposable domains
• Temporary email generators
• Alias services

Our database is updated daily with new disposable domains.

Stage 5: SMTP Verification

The most accurate but also most complex verification step. We:

1. Connect to the recipient's mail server
2. Initiate an SMTP conversation
3. Check if the specific mailbox exists
4. Handle various server responses gracefully

HELO verify.emailverify.ai
MAIL FROM:<verify@emailverify.ai>
RCPT TO:<user@example.com>
→ 250 OK (mailbox exists)
→ 550 User unknown (mailbox doesn't exist)

Stage 6: Score Calculation

We combine results from all stages to calculate a confidence score (0.0 - 1.0):

Verification Speed

Different verification levels have different speed profiles:

Handling Edge Cases

Catch-all Domains

Some domains accept all emails regardless of whether the mailbox exists. We:

1. Detect catch-all configuration
2. Flag the result as accept_all
3. Provide a moderate confidence score
4. Let you decide how to handle these addresses

Greylisting

Some servers temporarily reject first-time senders. We:

1. Detect greylisting responses
2. Implement automatic retry logic
3. Cache results for efficiency

Rate Limiting by Target Servers

To protect both EmailVerify and target mail servers:

1. We distribute verification requests across multiple IPs
2. Implement adaptive rate limiting per domain
3. Respect server-requested delays

Infrastructure

Global Verification Network

• Multiple Data Centers: US, EU, Asia-Pacific
• Redundant Systems: 99.9% uptime guarantee
• Smart Routing: Optimal path selection for each verification

Security & Compliance

• All connections encrypted (TLS 1.3)
• No email content ever stored
• GDPR compliant data handling
• SOC 2 Type II certified

Best Practices

When to Verify

Verification Frequency

• Active lists: Verify quarterly
• Inactive lists (90+ days): Verify before any send
• New acquisitions: Always verify before first use

Next Steps