Validation Methods

RS Email Verifier offers three depths. Each deeper method includes the earlier stages.

Basic

Basic is a fast local pre-screen. It checks formatting, structural patterns, role mailboxes, likely typos, trap keywords, official or local rules, and batch-level patterns.

Use it when:

• data must remain offline;
• you need an initial classification before more expensive checks;
• the list is very large and speed is the first priority.

A syntax pass alone is unknown, not proof that a mailbox exists.

DNS

DNS runs Basic and then queries MX records. If no mail server is available, the address becomes invalid. If the query times out or a proxy fails, the result is unknown rather than invalid.

Use it when you need domain-level evidence without contacting a recipient server.

SMTP PRO

SMTP PRO runs Basic and DNS, then connects to an available mail exchanger and performs greeting, HELO, MAIL FROM, and RCPT TO checks. A random-recipient probe helps identify catch-all or anti-enumeration behavior.

The probe stops before DATA; it does not transmit an email body. Port 25 access is required and may be restricted by a local network, ISP, cloud provider, firewall, or destination.

How stages affect one another

• A hard invalid result from format or policy rules stops later network stages.
• A soft risky result continues into DNS or SMTP PRO.
• A later positive result does not erase a stronger earlier risk.
• A timeout, blocked connection, or proxy failure normally produces unknown.
• Catch-all is risky because an accepting server response cannot identify whether the specific inbox exists.

Recommended workflow

For a new list, test a small sample in SMTP PRO first. Confirm network and proxy behavior, then choose the least expensive method that produces enough evidence for your audience policy.

Next: verify one address or run a batch.