Frequently Asked Questions
Everything you need to know about MailVeri email verification.
General Questions
What is email verification?
Email verification is the multi-stage process of checking if an email address passes syntax validation, belongs to an active domain with live MX records, is not a temporary disposable burner, and has an active mailbox confirmed via SMTP verification. It helps you maintain list hygiene and keep your bounce rate strictly under 2% before sending campaigns or transactional emails. Read our guide on why email verification is critical.
What is the meaning of each status in the report?
Each email returns one of seven actionable verification result statuses:
- VALID – Confirmed individual mailbox that exists and can receive messages safely (see why a 0.5% post-verification bounce floor exists)
- INVALID – Mailbox does not exist (550 5.1.1), syntax is broken, or domain has dead/Null MX records
- DISPOSABLE – Temporary burner email address (100,000+ tracked domains) that should be blocked at signup
- ROLE_ACCOUNT – Verified shared inbox (
info@,support@,billing@); see how to route role-based vs. disposable emails - CATCH_ALL – Domain accepts all incoming mail at the gateway; isolate to secondary domains in cold outreach
- FULL_INBOX – Mailbox is 100% over storage quota (SMTP 452) and cannot receive mail; pause sends for 30 days
- UNKNOWN – Destination mail server timed out or transiently deferred verification (0 credits charged)
What is a FULL_INBOX status, and why don't full mailboxes bounce immediately?
A FULL_INBOX status indicates that an email address exists and is active, but its storage quota has reached 100% capacity. Because there is zero storage space available, the destination mail server refuses to deliver incoming emails.
Why don’t full mailboxes bounce right away? In the SMTP specification (RFC 5321), mailbox quota rejection is commonly treated as a soft bounce deferral (SMTP code 452 User quota exceeded) rather than a permanent rejection (552). When sending services like Gmail, Google Workspace, Amazon SES, SendGrid, or Mailgun receive code 452, they do not generate an immediate bounce. Instead, they hold the message in an internal deferred retry queue for 24 to 48 hours, hoping the recipient will delete old emails to free up storage space. Only after 48 hours of repeated failed retries does the ESP finally give up and send a delayed bounce notice.
The risk to senders: In practice, over 95% of full mailboxes on free or abandoned domains are permanently inactive. If you send campaigns to them, these delayed bounces strike your sender reputation all at once 48 hours later, frequently pushing your bounce rate past ESP suspension limits (5% warning, 10% instant account ban). Read our technical deep dive on FULL_INBOX & 48-hour delayed bounce risks.
What file types do you support for bulk upload?
We support multiple file formats for bulk email verification (up to 1,000,000 rows per job):
- CSV – Comma-separated values files (
.csv) - Excel – Native Microsoft Excel spreadsheet files (
.xlsxand.xls) - TXT – Plain text files with one email per line (
.txt)
Exports from Apollo.io, Clay, HubSpot, Klaviyo, Instantly, and Smartlead work out of the box—see our Bulk Email Verification Walkthrough.
How long does verification take?
Single email verification returns in real time via our REST API & MCP server or our Free Email Checker. For bulk lists up to 1,000,000 rows, high-concurrency parallel batch processing completes lists quickly with live dashboard progress and optional webhook callbacks.
Do you send any emails during verification?
No, we never send any emails to verify addresses. Our SMTP verification handshake checks if a mailbox exists and closes the connection with QUIT before delivering any message—ensuring zero impact on your sender reputation. Learn more in How SMTP Email Verification Works.
How often should I re-verify my email list?
We recommend re-verifying your CRM every 90 days (3 months) and immediately before any major email campaign. Because corporate and consumer lists decay by 18%–22% annually due to job changes and abandoned accounts, regular email hygiene keeps your bounce rates under 1%. See our 2026 B2B Email Decay & Catch-All Benchmark and Email List Hygiene Playbook.
What is a catch-all server?
A catch-all domain is configured to accept all emails sent to a domain during the initial SMTP handshake, regardless of whether the specific individual mailbox exists. Unsegmented catch-all leads often trigger delayed NDR bounces that hurt deliverability. MailVeri flags these as CATCH_ALL at 1 flat credit (zero markup) so you can segment them safely—read Catch-All Emails Explained and our Catch-All Verification Cost Audit.
What is greylisting and how does MailVeri handle it?
Greylisting (RFC 6647) is an anti-spam deferral where a mail server temporarily rejects unfamiliar connections with a 4xx SMTP code (such as 451 or 421). When a destination server defers verification due to greylisting or temporary throttling, MailVeri returns an honest UNKNOWN status (at 0 credits billed) rather than guessing—see our Greylisting Explained Guide and 4xx vs. 5xx SMTP Bounce Codes Reference.
Can you verify Yahoo, Hotmail, and Outlook addresses?
Yes, we verify all major consumer and enterprise email providers including Gmail, Google Workspace, Yahoo, Outlook, Hotmail, Microsoft 365, iCloud, AOL, Zoho, and ProtonMail with 99%+ accuracy. Read our engineering guide on Verifying & Normalizing Free Webmail Providers.
Free Tools
Are the free tools really free?
Yes! All 8 of our free deliverability tools—Email Checker, MX Lookup, SPF Generator, DMARC Generator, Blacklist Checker, Bounce Rate Calculator, ESP Overpayment Calculator, and Domain Reputation—are 100% free to use directly on our website without creating an account.
Do you save the emails I check in the free tools?
We respect your privacy. For single checks in the Free Email Checker, recent checks are displayed only for your convenience. Uploaded bulk lists and verification exports are automatically purged after 30 days (or can be deleted immediately from your dashboard)—see our Privacy Policy and Security Architecture.
How is domain reputation calculated?
Our Domain Reputation Tool evaluates MX record validity, SPF, DKIM, and DMARC authentication alignment, and presence on major DNSBL blacklists to calculate a composite trust score and sender score from 0 to 100.
What is the limit for the free tools?
The web-based free tools have a generous daily limit to prevent automated abuse. For bulk CSV uploads or programmatic API access, create a free account to receive 1,000 free Universal Credits—or explore our pay-as-you-go pricing ($9 for 10K).
Credits & Billing
Zero forced monthly subscriptions. Buy credits once ($9/10K, $59/100K, $299/1M) and use them at your own pace forever.
Verify 10,000 emails for $9, 100,000 for $59, or 5,000,000 for $999 ($0.0002/email) while keeping bounce rates strictly under 2%.
Accurate CATCH_ALL domain detection and disabled mailbox (550 5.2.1) isolation are included in every standard 1-credit check.
Upload raw .csv, Excel (.xlsx, .xls), or .txt lists from 10,000 to 1,000,000+ rows per batch with zero manual format conversion.
Do credits expire?
No, your credits never expire! Unlike monthly subscription plans that forfeit unused quota at the end of every billing cycle, our Universal Credits remain in your account indefinitely for both bulk uploads and real-time API checks. View all credit packages on our Pricing page.
What payment methods do you accept?
We accept all major credit cards (Visa, Mastercard, American Express, Discover) and PayPal. All payments are processed securely via PCI-DSS Level 1 infrastructure. High-volume and Wholesale API customers can also request invoice-based billing via Contact Sales.
Can I get a refund?
Since we provide 1,000 free credits for every new account to test our verification accuracy and speed thoroughly before purchasing, we maintain a no-refund policy on credit purchases as detailed in our Terms of Service. We encourage you to test your own lists and API integration using your 1,000 free credits first.
How do credits work?
1 credit = 1 email verification across both bulk CSV/Excel uploads and real-time REST/MCP API calls. Credits are only deducted for conclusive verification results. Transient UNKNOWN results are automatically excluded from billing (0 credits charged)—learn more in Understanding UNKNOWN Email Status.
How does MailVeri compare in price to ZeroBounce, NeverBounce, or Hunter?
MailVeri is significantly more affordable, offering up to 90% savings. For example, 10,000 email credits cost $9 on MailVeri vs $129 on ZeroBounce ($50 on NeverBounce); 100,000 credits cost $59 on MailVeri vs $649 on ZeroBounce ($400 on NeverBounce, $740 on Hunter, $149 on MillionVerifier); and 1,000,000 credits cost $299 on MailVeri vs $3,199 on ZeroBounce ($2,500 on NeverBounce). Explore all 36 Head-to-Head Verifier Comparisons, our Q4 2026 Pricing Index Report, and our Verification ROI Calculator.
Can I verify large B2B sales lists from real estate, Apollo, or LinkedIn?
Yes! MailVeri is built for high-throughput bulk list cleaning (CSV, Excel) of up to 1,000,000 emails per batch across Outbound & Lead Gen Agencies, AI Startups, SaaS, E-Commerce, and Non-Profits. It verifies Apollo.io and LinkedIn exports to isolate catch-all domains, spam traps, role accounts, and disposable addresses—see Why Apollo “Verified” Emails Still Bounce.
Do you offer volume discounts?
Yes! Our pay-as-you-go pricing scales down to $0.0002 per email on our 5,000,000-credit package ($999). Standard tiers include 1,000,000 credits for $299 ($0.000299/email), 100,000 credits for $59 ($0.00059/email), and 10,000 credits for $9 ($0.0009/email). Need 10M–500M+ monthly checks? Check our Wholesale & White-Label API or earn 30% lifetime recurring commissions via our Affiliate Program.
Is there a free trial?
Do you offer monthly subscriptions?
Can I get an invoice for my purchase?
Integrations
Do you integrate with Zapier?
Yes, you can connect MailVeri to 5,000+ apps via our Zapier Integration. Trigger verifications automatically when a new lead is added to your CRM, form, or spreadsheet—see our step-by-step Zapier Email Verification Setup Guide.
Can I use MailVeri with WordPress and FluentCRM?
Yes! You can integrate MailVeri with WordPress and WooCommerce using our FluentCRM & WordPress Integration or our REST API (which includes drop-in PHP snippets for registration hooks and contact forms).
Do you support HubSpot, Klaviyo, and Mailchimp?
Yes! Explore our dedicated guides for HubSpot and Klaviyo, plus our playbooks on cleaning HubSpot & Pipedrive lists and cutting Klaviyo active profile costs by 30%. You can also estimate your monthly CRM savings using our ESP Overpayment Calculator.
How do I connect MailVeri to Make.com and Google Sheets?
We provide ready-to-import blueprints for both Make.com and Google Sheets. Follow our engineering tutorial on Verifying Emails Automatically in Google Sheets & Make.com.
How do I verify leads in Clay, n8n, Instantly, or Smartlead?
MailVeri is purpose-built for modern B2B outbound stacks: connect our Clay HTTP API Integration (see how to save 80% on Clay waterfall credits), automate multi-step routing with n8n (n8n workflow guide), and scrub leads before launching sequences in Instantly or Smartlead (Instantly & Smartlead bounce guide).
How does MailVeri prevent bounce suspensions on Amazon SES, Postmark, and GoHighLevel?
Strict transactional and agency ESPs enforce automated compliance locks when hard bounces cross 3%–5%. Explore our dedicated integrations for Amazon SES and GoHighLevel (LC Email), plus our guides on preventing AWS SES, Postmark & Resend suspensions and preventing GoHighLevel agency bounce locks.
API & Integration
Do you have an API?
Yes! We offer a comprehensive REST API & Developer Documentation that lets you integrate real-time single email verification and 1M-row batch processing directly into your signup forms, SaaS auth flows, and CRM pipelines. See our Email Verification API Integration Guide and Supabase, Clerk & Next.js Auth Guide.
What programming languages do you support?
Our REST API works with any language that can make HTTPS requests. We provide ready-to-run code examples for cURL, Python, Node.js/TypeScript, PHP, Ruby, and Go in our API Reference.
Is there a rate limit on the API?
Yes, for fair usage we apply rate limits. Free accounts support 10 requests per second, paid accounts scale higher automatically, and Wholesale API partners can provision custom high-throughput rate limits.
Do you offer webhooks?
Yes! You can configure webhook URLs to receive automated callbacks when bulk verification jobs complete, allowing asynchronous processing of large lists without polling. Read about our MailVeri 2.0 Webhook Specification in the API Docs.
How do I get an API key?
Can AI agents (Claude, Cursor, Windsurf, n8n) verify emails via Model Context Protocol (MCP)?
Yes! MailVeri provides an official Model Context Protocol (MCP) server (mailveri-mcp) so AI agents in Claude Desktop, Claude Code, Cursor, Windsurf, and OpenAI Agents SDK can verify single emails, check credit balances, and run 1,000,000-row batch verifications natively via tool calls. Explore our MCP Server Documentation and MailVeri MCP Guide for AI Agents.
Security & Privacy
Is my data secure?
Absolutely. All data is encrypted in transit using TLS 1.3 and at rest using AES-256 encryption. Our infrastructure is hosted on SOC 2 compliant cloud providers and undergoes continuous security monitoring—see our Security & Compliance Overview.
How long do you keep my uploaded data?
We automatically delete uploaded email lists and verification results after 30 days. You can also manually delete your data at any time from your dashboard. Review our full data retention commitments in our Privacy Policy.
Are you GDPR compliant?
Yes, MailVeri is fully GDPR compliant. We process data only for the purposes you specify, implement strict technical safeguards, and provide immediate data deletion upon request. Enterprise customers can request a signed Data Processing Agreement (DPA) via our Security & Legal Contact page.
Do you sell or share my email lists?
Where are your servers located?
Still have questions?
Our support team is here to help. Reach out and we'll get back to you within 24 hours.