TG Email Validator is a tool composed of two DLLs which validate addresses in 4 levels:Level 1 - Syntax: email address syntax validLevel 2 - Domain: email server (MX record) is configuredLevel 3 - SMTP: destination email server is runningLevel 4 - Account: email address exists Not all email servers support level 4 validation. Thus, if all other validations are passed we return a 250 OK response if the target email server does not support level 4 validation.Feel free to trial this using the form on our website. The string returned in below the submit button is what the DLLs wil return.