MailGuard Overview
MailGuardLast updated July 2026
What is MailGuard?
MailGuard is Scoor's real-time email verification widget. Embed one script tag on any page and MailGuard automatically attaches to every email input it finds — validating as users type, before form submission.
Bad leads cost you in two ways: wasted setter time calling numbers that don't answer, and ad spend that gets credited to leads who were never real. MailGuard stops both.
How it validates
MailGuard runs a multi-layer check on every email in under 300ms:
- Format check — RFC 5322 compliant format validation. Catches typos like
john@gmailcom. - Disposable provider check — Matches against a continuously-updated database of throwaway email providers (Mailinator, Guerrilla Mail, 10 Minute Mail, etc.).
- MX record lookup — Verifies the domain has valid mail server records. No MX = no inbox.
- SMTP verification — Connects to the mail server and checks the specific mailbox exists without sending an email.
- Free provider filter — Optionally blocks Gmail, Hotmail, Yahoo (useful for B2B funnels targeting business decision-makers).
Validation types
| Type | Example | Blocked by default? |
|---|---|---|
| Invalid format | john@, @gmail.com | Yes |
| Disposable provider | test@mailinator.com | Yes |
| Invalid domain / no MX | john@notarealdomain.xyz | Yes |
| Undeliverable mailbox | fakeuser@gmail.com | Yes |
| Free providers | john@gmail.com | No (opt-in) |
| Role-based emails | info@company.com, admin@ | No (opt-in) |
Accuracy & SLA
- Average validation response time: < 300ms
- API uptime SLA: 99.9%
- Disposable provider database: updated continuously
- False positive rate on legitimate business emails: < 0.1%
SMTP verification limits: Some corporate mail servers (Microsoft 365 in particular) reject SMTP probing. For these domains, MailGuard falls back to MX verification only and may return a
risky status rather than invalid. We recommend allowing risky through and flagging them for manual review rather than hard-blocking.Was this page helpful?