In today's digital marketing era we may have multiple ways to reach out to customers but emails are still considered the best and most cost-effective source.

The two major pillars that decide the success of any email marketing campaign are - the deliverability rate and open rate and both of them directly depend on the quality and management of the email lists.

At Clearout, we are committed to address and resolve all email deliverability issues such as bounces, danger to sender reputation by using a high-precision algorithmic method of determining the status of an email address in real-time. Clearout is specially designed for marketers, sales and product owners to help capture, clean, verify, discover the email address, this will gaurantee that email database or list will be in good state and can be used for email maketing or outreach campaigns with out concerned about deliverability issue thus expecting high return on investments (ROI)

Create a Free Account

Getting started with Clearout is free, easy, and does not require a credit card. Your account comes with 100 free email verification credits. If you need more, check out pricing for buying additional credits. The best part is that credits never expire. If you don’t have an account click here to create a free account

Bulk Verification

Once you have created and logged in your Clearout account, you can upload your emailing list for verification. Checkout the integration pages to know more about importing, verifying and exporting the email lists from all major ESPs and CRMs.

Quick Validation

As the name suggests, with quick validation you can get instant results. Once you have created an account, just go to quick validation, enter the email addresses you want to verify and click on 'Validate'. Maximum 10 email addresses are allowed per validation.

Apps and API

Clearout Apps is a unique way of creating multiple API tokens that can be used to integrate with various applications from a single Clearout's account. Clearout Apps enables the developer to decide how and where the validation needs to be performed by choosing run type either as client or server, this protects against mishandling of credits by setting the threshold at the domain, URL, and/or IP level. Also, Clearout Apps helps to measure and report the usage of the credit at an app level.

Clearout's advance email validation and verification service is available as a simple REST-based API that can be safely integrated on server-side applications. Users looking for client-side or custom integration should check JavaScript Widget that can be seamlessly integrated with all kinds of forms that capture email address with or without the minimal development effort.

Deliverability Guarantee

Email deliverability is the foundation of a successful email marketing program. If you’re not getting emails delivered, you don’t have a proper email marketing program. At Clearout we understand the importance of email deliverability, that's why we adopt the best practices for email verification to offer the best possible accuracy in the industry. We back up our verification results with a 97% deliverability rate guarantee. In other words, when you verify your email addresses with Clearout, we guarantee that the bounce rate will not be more than 3% in case of messages sent to “Guaranteed Deliverable” email addresses or the flag Safe-to-Send set as "Yes".

In order to qualify for our guarantee, the following criterias must be met-

  • Email addresses must be classified as the guaranteed deliverable
  • The email is sent anytime within 24 hours from the verified time
  • Email addresses must have been acquired by the Opt-in process only. Email addresses acquired by purchased or rented lists are not covered under this guarantee.
  • Free service providers such as Yahoo, AOL will not be covered
  • Bounces resulting from technical issues, poor sender reputation , recipient server reaching maximum receiving capacity, mail server being improperly configured, server not being available, or the recipient has specifically banned the sender's email identity, delivery blocked due to internal rules, etc. won't qualify for this guarantee.

Understanding Verification Results

Safe to Send

The safe-to-send flag is based on best practices followed in the industry, At times there can be a situation when even a valid email bounces back. There can be multiple reasons for the same, that's why we have introduced the safe to send feature. It provides the below-mentioned 4 values which determine how secure an email address is based on the probability of bounce-back

YesSending emails to these email addresses is completely safe as long as the email is sent anytime within 24 hours from the verified time.
RiskyAs the name suggests, a little risk is involved in sending emails to these email addresses but the email addresses of this result file are safe to use when the bounce rate is strictly below 5% or using own email sending platform without depending on external Email Service Provider (ESP).

The risk factor depends upon multiple reasons like

  • High volume of role-based email addresses
  • Any temporary mail account issue
  • Mail server configured to accept all email messages
NoInvalid email addresses that you should avoid sending emails to.
UnknownDue to unavoidable reasons, the status of the email cannot be determined currently


The status gives a broad picture of the quality of the email addresses. After successful email verification, every email address is primarily categorized as either Valid, Invalid, Catch-All or Unknown.

ValidA valid email address has been verified as a real email that is currently accepting the emails
InvalidAn invalid email address has been verified as a bad recipient address that does not exist or is not accepting the emails. Invalid emails will result in a bounce
Catch-allCertain servers accept all the emails for that domain and never bounces it back to the sender, those email addresses are flagged as catchall emails.
UnknownClearout will return an unknown result when it was unable to get a response from the recipient's mail server. This often happens if the destination mail server is too slow or temporarily unavailable due to an issue with their internal network or expired domain names. In certain cases, retrying your request after some time will return a valid or invalid response.

Status Reasons

Apart from the email verification results mentioned above, the report generated will contain the status reasons for the given status results. The definition of each status reason is explained below.

Status ReasonDescriptionClearout StatusBounce Type
SuccessThis email address is valid and safe to send emails.Valid
FailureThis email address belongs to a mail server that is returning a temporary errorUnknown
Syntax errorThis email address is a commonly misspelled popular domain according to RFC standards.InvalidHard
Probably Spamtrap/HoneypotThese email addresses are believed to be spamtraps, must avoid sending mails.InvalidSoft
Mail server connection timeoutUnable to connect to mail server with in stipulated time, recommend to retry some time laterUnknown
Domain not foundThis email address is valid in syntax, but the domain doesn't have any records in DNS or have incomplete DNS Records.InvalidHard
Not a Mail ServerThis email address doesn’t belong to a mail server.InvalidHard
Mail server errorThis email address belongs to a mail server that is returning a temporary error.Unknown
Mailbox not foundThis email address is valid in syntax but does not exist.InvalidHard
Mail server employed greylisting technique; so try after sometimeDomain IP of the specified email address is greylisted, advice to retry some time laterUnknown
Catch-All mail serverMail server has been configured to receive all messages that are addressed to an incorrect email address for a domainCatch-All
Unable to determine; retry later after an hour or soThis email address is not responding at the particular moment so you can retry later an hour or so.Unknown
Mailbox quota exceededThis email address exceeded the space quota and are not accepting any emails.InvalidSoft
Retry later after an hour or contact supportThe server didnot allow verification of the emails, temporarily. As we do not charge for the unknowns it is always advisible to retry verifying at a later point of time.Unknown
No Answer Received From Authoritative ServerThis email address belongs to a mail server that is not responding at the time of verification.Unknown
Dns Query TimeoutUnable to resolve DNS with in stipulated time, so retry at a later time increasing the timeout parameter(API verification)Unknown
Dns Query Unhandled ErrorThis 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 are not accepting any emails.InvalidSoft
Mail server command timeoutVerifying this email address takes a longer time than expected. Please retry at a later time increasing the timeout parameter(API verification)Unknown
An unexpected error has occurred while validatingUnexpected error occurred as part of the verificationUnknown
Email is part of allowlistYou have added email address part of the allowed list, so the validation result will always return as validValid
Email is part of blocklistYou have added email address part of the blocked list, so the validation result will always return as invalidInvalid
Domain is part of allowlistYou have added domain part of the allowed list, so the validation result will always return as valid for any email address with this domainValid
Domain is part of blocklistYou have added domain part of the blocked list, so the validation result will always return as invalid for any email address with this domainInvalid
Request CancelledYou have cancelled the email verification requestUnknown
Unsupported characterEmail address has an unsupported character, may be other than ASCII characterInvalidHard

Associated Results

Here are the other result related terms to help you get a better understanding

Disposable Email AddressClearout checks if the email address belongs to a temporary account created for a short period of time, like a few hours to a few days. Generally, disposable emails are created to receive initial account activation or confirmation emails for sites like discussion forums, e-shopping etc. Sending emails to such addresses increases the bounce rate. So it is highly recommended not to send emails to "Disposable Email Addresses".
Free Email AddressClearout identifies the email addresses that are using free services such as Gmail and Yahoo! Mail. In many cases, it is perfectly acceptable to send email to a user of a free email service. However, in certain contexts, businesses can receive better open/response rates when only sending to non-free email addresses.
Role Based Email AddressClearout identifies the email addresses that are typically associated with a role (postmaster, support, sales, etc.) instead of a person. In some instances, mailing to a role address can lead to a decreased open rate and is generally advised against while sending an email
Gibberish Email AddressClearout identifies the email addresses that are very likely meaningless. Generally such type of account will be created for the cause of doing some kind of unethical activities
MX RecordClearout real-time verification resolves and determines the existence of an email address by using the best MX record for the given email domain. This information will be captured and returned as part of the bulk verification result file or the API response object
SMTP ProviderClearout finds the STMP provider of the mail exchange for the given email domain. This helps in determining how to use the recipient's email address for email campaigns
Auto suggestionClearout provides autosuggestion feature which checks in real-time if there is a typo. The autosuggestion will pose an alternative email address when Clearout notices a potentially mistyped address. For instance, if a user types the email address as "[email protected]", Clearout will suggest the corrected spelling [email protected].
Verification TimestampClearout provides the verified time for every email address to ensure the freshness of your list.
Verification Time TakenClearout provides the response time taken for every email address by a simple open relay check.

Turnaround Time (TAT)

Real-time verification through Clearout API is exceptionally swift, taking less than a second for major free email service providers like,,, and, which collectively cover a substantial share of the email population. Clearout has optimized the turnaround time even for business email addresses created using G-Suite, Microsoft Exchange Servers, and Yahoo businesses.

Moreover, our email verifier boasts impressive efficiency, as it takes an average of 30-45 minutes to validate an email list containing 100,000 contacts. Better yet, our email verification services validate an email address in approximately 0.027 seconds, ensuring a rapid and accurate screening process for enhanced email list hygiene. It's worth noting that the validation time for business domains may vary depending on the type of domains included in the bulk list, reflecting our commitment to adaptability and precision in email verification.

In addition to the above, Clearout offers two modes of list verification:

1. Highest Accuracy: This verification mode guarantees the best quality email addresses, ensuring deliverability to the mailbox without bounce. While it may take longer due to multi-stage validation with advanced anti-greylisting techniques, the result yielded is top-notch and unbeatable in quality.

2. Fastest Turnaround: Opting for this verification mode generates results much faster. By passing through limited-stage validation, skipping anti-greylisting and no retry for slower mail exchangers, it delivers quicker results. This mode may result in more unknowns, but it does not compromise the quality of the results.

Security and Privacy

We, the Clearout team, completely understand the sensitivity and importance of your email data, that's why we give our best to keep your data secure and private. Clearout's service is fully compliant with the GDPR and we committ in never selling or sharing the addresses you verify using our system.

Security of your uploaded / imported data

The following measures are taken to protect the data you upload, import or use during quick validation

  • List data is transmitted over 256-bit SSL, the same protocol used by financial firms to ensure secure data transmission.
  • Your data is never stored in our system for more than 30 days after processing. Once you finish using our system, all information related to your account will be erased in a maximum of 30 days. You may also delete your results any time before the 30-days as an added precaution.
  • We have also developed advanced defense mechanisms against misuse, loss, unauthorized access, and improper disclosure of your data.

Security of API Data

Email addresses verified using Clearout API are protected during transmission using 256-bit SSL. In addition to data encryption in transit and at rest, we process the data under the rules of our privacy policy with an access control mechanism. We do not entertain user data for any purpose other than validation. For further detailed information, you can refer to our privacy policy