Overview
Multi-layer validation checks for accurate, reliable email deliverability
Clearout Email Verifier ensures every email address you collect or use is valid, reachable, and safe to send. It combines real-time checks, mailbox-level diagnostics, and risk detection to prevent bad data from entering your CRM, marketing, or outreach workflows.
Whether you are validating form submissions instantly or cleaning millions of records in bulk, Clearout delivers high-confidence results without sending any emails, keeping your sender reputation protected.
Different Ways of Email Validation
Clearout supports multiple validation workflows to match how your teams collect and manage email data
Understanding Email Verification Results
Email deliverability is critical for successful email programs. Clearout backs its verification results with a 99% deliverability rate guarantee.
When you verify email addresses with Clearout, the bounce rate will not exceed 3% for messages sent to "Guaranteed Deliverable" email addresses or addresses where the Safe-to-Send flag is "Yes" provided all qualifying criteria are met. Criteria to qualify for Guaranteed Deliverability
Email addresses must be classified with the Safe-to-Send flag as Yes
Emails must be sent within 24 hours of the verification time.
Email addresses must have been acquired via an opt-in process; purchased or rented lists are excluded from the guarantee.
Free service providers such as Yahoo and AOL are excluded.
Mail servers behind certain anti-spam settings (for example, Microsoft 365) do not qualify.
Bounces caused by technical difficulties, poor sender reputation, server capacity limits, misconfiguration of the mail server, server unavailability, or deliveries blocked due to internal rules or explicit sender blocks are not covered
Safe To Send
The Safe-to-Send flag is based on industry best practices. In some cases, valid email addresses can still bounce for reasons beyond syntax or mailbox existence, so the Safe-to-Send flag indicates how safe an address is to use based on the probability of a bounce
Yes
Sending emails to these addresses is safe, provided emails are sent within 24 hours of the verification time.
Risky
There is some risk associated with sending to these addresses. They are generally usable when the bounce rate must remain below 5% or when using your own sending infrastructure instead of an external Email Service Provider (ESP).
No
Invalid email addresses that you should avoid sending to.
Unknown
The status of the email cannot be determined at this time due to external or temporary factors.
The risk factor depends upon multiple reasons, like
Mail servers that are incorrectly configured
Unusual SMTP response
Any temporary mail account issue
Mail servers configured to accept all messages with anti-spam protection that reveals true status only when sending (for example, some Office 365 domains)
Status
Clearout categorizes email verification status into four primary statuses: Valid, Invalid, Catch All, or Unknown. These statuses indicate the real-time deliverability of a given email address.
Valid
A valid email address has been verified as a real mailbox that is currently accepting email.
Invalid
An invalid email address has been verified as a bad recipient that does not exist or is not accepting email and will result in a bounce.
Catch All
It's a domain-level setting that accepts messages sent to any address under the domain, including invalid ones. Messages may be rejected later due to spam filters, mailbox limits, or security rules, so the "safe to send" status is marked as "risky".
Unknown
This unknown status occurs when Clearout fails to receive a response from the recipient’s mail server. This event often occurs when the mail server is slow or temporarily unavailable. In some cases, retrying later returns a valid or invalid result.
Sub-Statuses with Reason
Further details that provide more context on the primary status
Success
This email address is valid and safe to send emails to.
Valid
Failure
This email address belongs to a mail server that is returning a temporary error.
Unknown
Syntax error
A syntax error in an email address occurs when the address does not follow the proper format defined by email standards (RFC 5322).
Invalid
Hard
Probably Spamtrap/Honeypot
These email addresses are believed to be spam traps and must not be used for sending.
Invalid
Soft
Mail server connection timeout
Unable to connect to the mail server within the expected time; retry later.
Unknown
Domain was not found
This email address is valid in syntax, but the domain doesn't have any records in DNS or have incomplete DNS Records.
Invalid
Hard
Not a Mail Server
This email address doesn't belong to a mail server.
Invalid
Hard
Mail server error
This email address belongs to a mail server that is returning a temporary error.
Unknown
Mailbox was not found
This email address is valid in syntax but does not exist.
Invalid
Hard
Mail server employed greylisting technique; so try after sometime
Domain IP of the specified email address is greylisted, adviced to retry sometime later.
Unknown
Catch All mail server
Mail server has been configured to receive all messages that are addressed to an incorrect email address for a domain.
Catch All
Unable to determine; retry later after an hour or so
This email address is not responding at the moment so that you can retry later an hour or so.
Unknown
Mailbox quota exceeded.
This email address exceeded the space quota and is not accepting any emails.
Invalid
Soft
Retry later after an hour or contact support
The server did not allow verification of the emails temporarily. As we do not charge for the unknowns, it is always advisable to retry verifying at a later point in time.
Unknown
No Answer Received From Authoritative Server
This email address belongs to a mail server that is not responding at the time of verification.
Unknown
DNS Query Timeout
Unable to resolve DNS within the stipulated time, so retry at a later time, increasing the timeout parameter (API verification).
Unknown
DNS Query Unhandled Error
This email address belongs to a mail server that is returning a temporary error.
Unknown
Insufficient System Resource (disk/memory)
This email server exceeded the space quota and is not accepting any emails.
Invalid
Soft
Mail server command timeout
Verifying this email address takes a longer time than expected. Please retry at a later time, increasing the timeout parameter(API verification).
Unknown
Account disabled
Mailbox associated with the email account is disabled.
Invalid
Hard
Associated Results
Associated result fields provide additional context about each email address beyond the primary status
Disposable Email Address
It is recommended to exclude email addresses from temporary mailbox services, which are intended for short-term use, to avoid higher bounce rates.
Free Email Address
Email addresses from free providers like Gmail or Yahoo are acceptable to use, but non-free domains may perform better in some cases.
Role-Based Email Address
Email addresses tied to a function (for example, support@ or sales@) rather than a person are generally not recommended for marketing emails.
Autosuggestion
When a potential typo is detected in the domain (for example, [email protected] → [email protected]), the system suggests a correction; these suggestions are not pre-verified.
MX Record
The Mail exchange (MX) record is used to route email for the domain and is returned in both bulk verification results and API responses.
SMTP Provider
Email service provider handling mail exchange for the domain; useful for deciding how to treat the address in campaigns
Verification Timestamp
Date and time when the email address was verified, used to assess list freshness
Verification Time Taken
Time taken to complete verification for the email address, in milliseconds
Clearout Standard Columns
The Clearout standard columns are additional data fields that can be appended to your original list after an email verification process to provide comprehensive information about the quality and status of each email address
Clearout Safe to Send
Indicates whether it is safe to send to the address.
Values: Yes, Risky, No, Unknown
Clearout Verification Status
Indicates the verification status of the email address.
Values: Valid, Invalid, Catch All, Unknown
Clearout Reason
Determines the reason for the current status of an email address. Multiple reasons described below.
Clearout Suggested Email
Suggestions on what the valid email address could be. Mostly helpful in case of typos.
Clearout Bounce Type
Invalid email addresses are categorized as Hard bounce & Soft bounce.
Clearout Disposable Status
Whether an email address is disposable or not.
Categorized as Yes or No.
Clearout Free Account Status
Whether an email address belongs to a free email provider or not.
Categorized as Yes or No
Clearout Role Account Status
Whether an email address is a role account or not.
Categorized as Yes or No
Clearout Gibberish Status
Calling attention towards random email addresses.
Categorized as Yes or No
Clearout Account
Identification of a probable name of the holder of the email address.
Clearout Domain
Identification of a probable domain name to which the email address belongs.
Clearout MX Record
Shows the MX record for the given email domain of the email address under verification.
Clearout SMTP Provider
Shows the STMP provider of the mail exchange for the given email domain.
Clearout Verified At (UTC)
Provides the exact time at which the email address was verified.
Clearout Time Taken (ms)
Time taken to verify the email address, in milliseconds.
Verification Settings
Clearout offers flexible settings to tailor validation behavior to your use case, such as options for real-time verification or batch processing, depending on your specific needs.
Bulk Verification Mode
Clearout provides multiple validation modes based on accuracy and speed requirements.
Fastest Turnaround - Optimized for extreme speed. The system provides a swift first-pass filter for large, unvetted data sets.
Highest Accuracy - Gold standard for list cleaning. It safeguards your sender's reputation by maintaining bounce rates below 3%.
Choose the mode that best fits your workflow.
Gibberish Threshold Value
Adjust the gibberish threshold to control how strict the gibberish validation check is during real-time validation
Off
Skip the gibberish check
Medium
Apply a moderate level of gibberish detection
High
Apply a strict check to determine whether an email address is gibberish
Allowlist / Blocklist (ABL)
Blocklist and Allowlist settings let you control which emails and domains are allowed or blocked at the point of entry. You can create filters for specific email addresses, patterns, domains, wildcard domains, or TLDs.
Data Retention
Clearout follows strict data retention and privacy practices.
Validation data is stored only as long as necessary (default 30 days)
Retention is configurable from 1 to 45 days
Data is handled in a GDPR- and compliance-friendly manner
Your data stays secure, private, and under your control.
Credit charge
Clearout follows a transparent credit usage model.
1 credit is charged per email validation, excluding the Unknown result status.
Credits are consumed only when validation is performed
Duplicate email addresses within the same list are not charged.
This ensures predictable usage and cost control at scale. Click here to read about credit charges in detail.
Supported Integrations
Clearout integrates seamlessly into your existing tech stack.
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