How does MailboxValidator work?

The Complete Guide to Email List Validation #

MailboxValidator is a highly intuitive, easy-to-use email address validation service. Users can quickly verify a single email address or perform bulk validation on large subscriber lists.

Using an enterprise email address verifier significantly lowers your overall digital marketing campaign costs. After completing the verification process, your database will contain far fewer stale email addresses.

Consequently, this data cleanup translates directly into fewer hard bounces. Ultimately, you will achieve superior sender reputation scores across all major inbox providers.

1. Validating a Single Email Address #

Single email validation is a straightforward process designed for quick individual lookups.

• The Web Interface: Sign into your user dashboard and select Single Validation. Enter the target email address into the text field, then click the Validate button. Your comprehensive results will appear on screen after a short while.
• The Developer API: You can easily integrate this real-time validation directly into your own applications or signup forms. Please visit our dedicated Single Validation API page for technical documentation.

2. Validating Large Lists of Email Addresses #

For massive databases, select the Bulk Validation option located within the same user dashboard. Simply select your subscriber file and press the Upload & Process button.

Processing times naturally scale based on the volume of data submitted. For example, a standard list of 500,000 emails takes approximately one full day to complete verification.

Supported Upload Formats #

Our automated parsing engine accepts two common file structures for bulk processing.

Plain Text Files (*.txt): A simple, clean list containing exactly one email address per line.

sam@example.net
james@example.net
sandra@example.net

Comma-Separated Values (*.csv): A multi-column database where our system automatically detects the correct email field.

“23234”,”James Warner”,”james@example.net”,”California”
“42133”,”Sandra Lim”,”sandra@example.net”,”New York”
“62134”,”Samuel Bishop”,”sam@example.net”,”Washington”

Once the validation concludes, the system transmits an automated notification email. You can then log back into the portal to view the data or download the full CSV report.

Note on Processing Queues: All uploaded bulk files enter a systemic processing queue. If your file shows no immediate progress, it is safely waiting its turn. Rest assured that our platform will process your file in due time.

3. Understanding Your Email Validation Results #

Your exported CSV result file contains several specific boolean attributes. Review the definitions below to interpret your data accurately:

Field Name	Data Type	Description
domain	String	The specific domain portion extracted from the email address.
is_free	Boolean	Indicates if the account belongs to a free provider like Gmail.
is_syntax	Boolean	Confirms whether the email address format complies with RFC standards.
is_domain	Boolean	Verifies the existence of valid MX records in the domain’s DNS entries.
is_smtp	Boolean	Confirms if the designated mail servers actively respond to network connections.
is_verified	Boolean	Indicates if the remote mail server confirms the mailbox actually exists.
is_server_down	Boolean	Identifies whether the target mail server is currently unresponsive.
is_greylisted	Boolean	Notes if the server uses greylisting protocols requiring a delayed secondary attempt.
is_disposable	Boolean	Flags temporary email addresses created through burner inbox providers.
is_suppressed	Boolean	Indicates whether the email matches internal blacklists or suppression files.
is_role	Boolean	Flags administrative or functional email addresses like admin@ or support@.
is_high_risk	Boolean	Identifies if the address contains known high-risk or spam-associated keywords.
is_catchall	Boolean	Confirms if the domain utilizes a catch-all configuration for all incoming mail.
mailboxvalidator_score	Float	Reputation rating where >0.70 is Good, >0.40 is Fair, and ≤0.40 is Poor.
time_taken	Float	The total duration in seconds required to process the specific address.
status	Boolean	The final programmatic verdict stating whether the email address is valid.