GoEmailValidator - Bulk Email Verification & List Cleaning Software

GoEmailValidator is a configurable bulk email verification, filtering, and list-cleaning solution designed for processing small lists as well as large email databases. It combines syntax validation, DNS analysis, SMTP recipient verification, web-based validation, blacklist filtering, disposable-email detection, generated-address heuristics, and many additional checks in one application.

The software runs the main processing workflow on your own computer or server, giving you control over validation rules, concurrency, DNS resolvers, proxies, result categories, and data files. Network-based checks connect to DNS, SMTP servers, or configured web endpoints only when the corresponding validators are enabled.

Main Email Validators

• Email Syntax Validator - checks the email structure, local part, domain part, separators, and invalid address formats.
• IDN and Punycode Validator - normalizes internationalized domain names and converts supported Unicode domains into their ASCII Punycode representation.
• ICANN Public Suffix Validator - verifies that the domain uses a recognized public domain suffix.
• DNS MX Validator - resolves the domain's mail exchanger records and identifies domains without usable mail servers.
• Null MX Validator - detects RFC 7505 Null MX records published by domains that explicitly do not accept email.
• SPF Validator - optionally checks whether the domain publishes an SPF record.
• DMARC Validator - optionally checks whether the domain publishes a DMARC policy.
• DNSBL A Validator - checks domain IP addresses against configurable DNS blacklist services.
• DNSBL MX Validator - checks mail server addresses against configurable DNS blacklist services.
• SMTP Recipient Validator - connects to available MX servers and checks how the destination server responds to the recipient during an SMTP session.
• SMTP Catch-All Validator - sends several randomized recipient probes to detect domains that appear to accept every address.
• SMTPUTF8 Support - allows validation of international local parts containing non-ASCII characters when the receiving SMTP server advertises SMTPUTF8 support.
• Built-In Web Validators - includes more than 20 service-specific web validation integrations with configurable priority, timeouts, proxy retries, and hard or soft validation modes.
• JSON-Configurable Web Validators - includes several pre-built JSON configurations and supports custom HTTP validation workflows loaded from the configs directory.

Built-In Email Filters

• Input Normalization Filter - extracts and normalizes email addresses from source lines while preserving the original input for result output.
• Email Blacklist and Wildcard Filter - blocks complete addresses or patterns using exact, prefix, suffix, and contains matching.
• MX Blacklist Filter - rejects addresses whose mail exchangers match configured MX hostnames or masks.
• Disposable Email Filter - detects temporary and throwaway email domains using a local database.
• Automatic Disposable Database Updates - periodically downloads an updated disposable-domain list from a configurable source.
• High-Volume and BIG-Domain Filter - filters known high-volume email domains using start and end lists.
• Automatic BIG-Domain Detection - can identify frequently repeated domains and MX hosts while a list is being processed.
• TLD Blacklist Filter - rejects domains matching configured top-level-domain or suffix masks.
• Free Email Provider Filter - optionally separates or rejects addresses from public free-email providers.
• Role Address Filter - detects generic mailboxes such as admin@, support@, abuse@, sales@, and other configurable roles.
• IDN Homograph Filter - detects suspicious mixing of Latin and Cyrillic characters inside an internationalized domain label.
• Typo-Domain Filter - detects known misspellings such as domains with swapped, missing, or incorrect characters using the editable typo_domains.txt database.
• Generated Email Heuristics - assigns a configurable suspicion score using UUIDs, hashes, encoded tokens, random strings, Shannon entropy, excessive digits, missing vowels, repeated patterns, character sequences, dates, timestamps, long local parts, random aliases, relay domains, and batch-level patterns.
• SMTP Response Filter - classifies SMTP rejections, provider blocks, and other server responses using editable text masks.
• Failed-Domain Filter - optionally remembers domains with repeated SMTP connection failures and prevents unnecessary repeated attempts.
• Large Whitelist Filter - stores whitelist entries in a disk-backed BadgerDB index, allowing very large whitelist databases to be searched without loading the entire list into RAM.
• Duplicate Result Filter - optionally removes duplicate valid addresses after processing.

Performance and Processing Features

• Configurable multithreaded processing for high-volume email lists.
• Adjustable worker count and goroutine start delay.
• Separate DNS cache TTL values for MX, A/AAAA, NXDOMAIN, and temporary DNS failures.
• Primary and alternative DNS resolver pools with configurable retries and query timeouts.
• SMTP retry logic with increasing delays for temporary failures.
• Multiple SMTP catch-all probes for more reliable catch-all detection.
• SMTP server caching to reduce repeated DNS and server discovery work.
• Configurable SMTP HELO/PTR strategies.
• Periodic result flushing and input checkpoints.
• Optional rechecking of bad and error results.
• Separate history and result directories.
• Detailed diagnostic logging and live processing statistics.

Proxy Support

GoEmailValidator supports flexible proxy use for compatible validation methods:

• Direct connections without a proxy.
• SOCKS4 proxies.
• SOCKS4A proxies.
• SOCKS5 proxies.
• Authenticated HTTP proxies for supported web validators.
• Random or sequential proxy rotation.
• Proxy loading from a local file, explicit list, range, or HTTP URL.
• Automatic proxy-list refresh with configurable intervals.
• Independent timeout and retry settings for individual web validators.
• SMTP validation through a proxy requires SOCKS4, SOCKS4A, or SOCKS5 proxies that explicitly support outbound TCP connections on port 25.

Flexible Web Validation

Built-in web validators can be enabled individually and executed in a configurable order. Each validator supports one of two operating modes:

• Hard mode - a positive result accepts the address, while a confirmed negative result stops further validation.
• Soft mode - a positive result accepts the address, while a negative or unavailable result allows later validators to continue.

Cross-Service Email Presence Score

check_validator_hard_test_percent is one of the most important web-validation options in GoEmailValidator. It checks whether an email address receives positive results from multiple enabled web validators instead of relying on only one service.

An address found by several independent services may have a broader digital footprint and is more likely to have been used for registrations or online accounts. This provides an additional confidence signal when evaluating the practical usage history of an email address.

• 0 – percentage-based evaluation is disabled. A positive result from the first suitable web validator can accept the address.
• 1–100 – defines the minimum percentage of applicable enabled web validators that must return a positive result.
• 25–35% – low threshold; useful for broad detection but provides weaker confidence.
• 50% – balanced threshold; at least half of the applicable validators must return a positive result.
• 70–80% – strong cross-service presence requirement.
• 100% – maximum strictness; every applicable validator included in the calculation must return a positive result.

Example: If six applicable web validators participate in the check and check_validator_hard_test_percent=50, at least three validators must return a positive result before the address is classified as valid by the percentage rule.

For meaningful percentage-based evaluation, enable several relevant web validators and normally configure them in soft mode (check_validator_*=2). Soft mode allows later validators to run when an earlier service returns a negative result or cannot confirm the address. A validator running in hard mode may stop processing before the complete cross-service score can be calculated.

Positive results that do not reach the configured threshold can still be stored separately, allowing the operator to review partially confirmed addresses and apply a custom decision policy.

Important: This feature estimates cross-service presence, not recent activity. It cannot prove that the mailbox is currently being read, that the owner still uses it, or when it was last accessed. The score also depends on the selected validators, their availability, and their ability to identify the address.

Generated Email Detection

The generated-address filter goes beyond simple regular expressions. Every address receives a suspicion score based on multiple independent signals. The final threshold, entropy sensitivity, minimum analyzed length, long local-part threshold, and batch-detection limits can all be adjusted in settings.ini.

Batch analysis can detect multiple addresses with similar machine-generated structures on the same domain. Detected addresses are written to a separate result category together with the score and reasons, allowing you to review the decision instead of receiving only a generic valid or invalid status.

Organized Validation Results

Results are separated into clear categories instead of being placed into one combined output file. Depending on the enabled checks, the software can produce separate files for:

• Valid addresses.
• Invalid recipients.
• Invalid or unavailable MX domains.
• Temporary network and validation errors.
• Catch-all domains.
• SMTP blocks and bans.
• Disposable email domains.
• Generated or suspicious addresses.
• Role-based addresses.
• Free email providers.
• BIG and high-volume domains.
• Domain, email, MX, and TLD blacklist matches.
• Positive results from individual web validators.

Optional Email Test-Data Generator

The software also includes a configurable email-address generator based on name, surname, domain, additional-value, and format-template dictionaries. This mode can be used for controlled QA, software testing, internal data preparation, and authorized research. Generated-address heuristic filtering is automatically skipped while generator mode is active.

Why Choose a Self-Hosted Email Validation Tool?

Most online email validation platforms charge for every address or require recurring credit packages. That model can become expensive when processing large databases or performing regular list maintenance.

GoEmailValidator provides a self-managed alternative. Validation runs on your own infrastructure, and the software does not require purchasing a new validation credit for every address processed. For high-volume workflows, this can significantly reduce the cost per verified record compared with continuously paying a third-party service.

Actual operating costs can still include internet access, proxies, server resources, DNS infrastructure, maintenance, and any third-party endpoints you choose to use. However, you retain control over these resources and can select only the validation methods required for each project.

Key Advantages

• No dependency on per-address validation credits - process lists using your own available infrastructure.
• Suitable for large databases - multithreading, caching, disk-backed whitelist storage, and categorized output support high-volume workflows.
• Fully configurable - enable only the validators and filters appropriate for your project.
• Transparent results - understand why an address was classified instead of receiving only a single score.
• Expandable architecture - add custom typo lists, blacklists, role lists, disposable domains, SMTP response masks, and JSON-based web validators.
• Local data control - input lists, caches, whitelist indexes, history, and output files are managed on your own system.
• Multiple validation layers - combine syntax, DNS, SMTP, web validation, and local filters.
• Resilient processing - configurable retries, alternative DNS resolvers, proxy rotation, checkpoints, and error rechecking.

Possible Use Cases

• Cleaning customer and CRM databases.
• Preparing authorized mailing lists before a campaign.
• Removing malformed, disposable, generated, role-based, or risky addresses.
• Checking imported subscriber lists during platform migration.
• Auditing registration data collected by your website or application.
• Separating free-email, business-domain, catch-all, and temporary addresses.
• Reducing avoidable bounce rates before sending legitimate email.
• Preparing segmented databases for internal analytics.
• Performing authorized data-quality checks for clients.
• Building an internal email-validation workflow for a company or agency.
• Providing paid email-list cleaning and validation as a professional service.

Use It to Offer Email Validation as a Service

GoEmailValidator can also become the technical foundation of a small email-list cleaning business. Agencies, data specialists, developers, and marketing professionals can process authorized client databases and charge for validation by list, project, record volume, or recurring maintenance plan.

For example, you can offer:

• One-time email database cleaning.
• Validation priced per 1,000 or 100,000 records.
• Recurring monthly list-maintenance packages.
• CRM migration and database-quality audits.
• Separate reports for valid, invalid, catch-all, disposable, role, and risky addresses.
• Custom filtering based on a client's business requirements.
• Private, locally processed validation for clients who do not want to upload lists to a public SaaS platform.

Because processing is performed using infrastructure under your control, you can define your own service packages, processing limits, validation depth, result format, and pricing model. This makes the software useful not only as an internal tool, but also as a foundation for an authorized commercial data-cleaning service.

SMTP Validation Requirements

SMTP validation requires the ability to establish outbound TCP connections to mail servers on port 25. When SMTP validation is performed through proxies, you must provide a working SOCKS4, SOCKS4A, or SOCKS5 proxy list with outbound port 25 support.

• Regular HTTP proxies cannot be used for SMTP validation.
• Proxies that block outbound port 25 will produce connection errors and cannot verify SMTP recipients.
• Many public and commercial proxy providers disable port 25, so compatibility should be confirmed before purchasing or importing a proxy list.
• Direct SMTP validation can be used without proxies only when your server, hosting provider, ISP, firewall, and network allow outbound TCP connections on port 25.
• Proxy quality, reputation, stability, and SMTP server policies can affect validation speed and results.

Bonus Software & Tools Included

Every purchase also includes access to a collection of bonus utilities designed to complement GoEmailValidator and simplify common email, content, link, and data-processing workflows.

The bonus package is provided at no additional cost and may include:

• Automatic URL Shortening Tools - process and shorten links through multiple supported URL-shortening services instead of creating every short URL manually.
• Multi-Service Image Uploading Tools - automatically upload images to supported image-hosting platforms and receive ready-to-use image links.
• Link Processing Utilities - prepare, convert, organize, and process large collections of links for different workflows.
• Content and Data Utilities - additional tools for preparing, transforming, and managing data used in online projects.
• SMTP Checking Utilities by Request - additional tools for testing and organizing authorized SMTP servers or accounts are available after purchase through a support ticket.
• Email Sending Software by Request - additional software for managing permission-based email campaigns may be provided after purchase through a support ticket, subject to current availability and applicable license conditions.
• Other Bonus Tools - additional useful software and utilities may be available upon request depending on the buyer's workflow and the currently available bonus collection.

Bonus utilities are separate from the core GoEmailValidator application and are not required for its normal operation. The exact selection may be updated over time as third-party services, APIs, and supported platforms change.

Some bonus tools may require an account, API key, proxy, paid third-party plan, or available credits from the corresponding external service. Access to third-party platforms is not included unless explicitly stated.

Responsible Use: Email campaign and SMTP-related tools must be used only with systems and recipient databases that you own or are authorized to process. Unsolicited mailing, unauthorized account checking, abuse of third-party services, and violations of privacy or anti-spam laws are not permitted.

Important Notes

• No validation method can guarantee future email delivery or prove that a mailbox belongs to a particular person.
• SMTP servers may use catch-all delivery, greylisting, rate limits, temporary blocks, delayed rejection, or anti-verification protection.
• SPF, DMARC, DNSBL, generated-address, and reputation checks describe domain characteristics or risk; they do not independently prove that a specific mailbox does not exist.
• Web-based validators depend on external endpoints that may change, restrict automated access, or become temporarily unavailable.
• Proxy quality, DNS resolver availability, network configuration, and remote-server policies can affect validation results.

Responsible Use: Use GoEmailValidator only with email databases that you own or are authorized to process. When providing validation services for clients, obtain permission, protect uploaded data, define a retention and deletion policy, and comply with applicable privacy, anti-spam, data-protection, and third-party service rules.