Email Validation

Email Validation

Validating your email addresses allows you to reduce your bounce rates, terminate invalid email addresses, prevent IP addresses and domain names from blacklisting you and improve your sender reputation. This section answers all your queries related to our email validation services, including our processing times, data retention policies and understanding the email validation results.

1 Credit = 1 Email Verification


Purchased Credits:

Credits can be used in the following ways:

  • Clean via List Upload in Dashboard
  • Verify using the Real-Time Widget
  • Verify one at a time via your Dashboard


How to upload a file?

Our system is built to upload TXT, XLS and CSV files. However, in order to avoid any errors, here are a few factors to keep in mind that can make the upload process smoother:

  • The first row in your list must have FIELD NAMES.
  • The list should have ONLY ONE email address in each row.
  • There should not be more than one million email addresses and 50 columns in your list. Additionally, the size must not exceed 200 MB.
  • It is recommended that you open your list in Google Sheets, OpenOffice Calc, Microsoft Excel or any other spreadsheet editor and save it as a CSV or XLS file before uploading it so that it is accurately formatted.


If you upload a file with an invalid file type extension such as DOC, DOCX, ODT, or PNG, you will get the following error message- “Invalid file type. File type should be TXT, XLS and CSV files”

If you upload a valid file type TXT, XLS and CSV files, it will upload successfully.

Is it possible to use multiple/other columns in my list?

Yes, you are free to use up to 50 other columns of data as required. However, you must contain all your emails in one column. After cleaning, your data will retain the same old format.

Acceptable Files

More often than not, when a list fails, it’s because it wasn’t converted into the desired format properly. However, not to worry. Fixing this is actually quite easy.

First of all, the best way to fix the formatting error of a list is to open the file in any spreadsheet editor and save it again as a CSV file. Here’s how you can do this:

  • For small lists, you can use any of the popular spreadsheet editors.
  • For large lists, CSVed is an excellent program option. You can use it free of charge, and it is very adept at handling large amounts of data. To download CSVed, click here
  • For very large lists, you can get in touch with our customer support team so we can help you manage these files.
  • Another error that you can encounter is with non-accepted characters. We recommend opening your list in a text editor such as text-edit or Notepad. Then, identify characters that don’t seem standard. If you can’t find them, you can use Find and Replace to switch out those characters for space. Once you have finished trying both these tricks, you can upload the list again.

If the error still persists, you can get in touch with our team, and we would be happy to answer your queries.

File Indexing

Sometimes you may find a difference between the number of records in your file to be validated and the actual number of email addresses prepped for validation by Bytesignal. There are a few reasons why this may happen. Consider the following:

  • Bytesignal indexes a list before validating it. This involves a thorough inspection of the file to note the email addresses that require validation. This means any duplicate, uni-coded and malformed records are deleted automatically during indexing by Bytesignal. These include:
    – Blank cells in the email address column
    – Title/header row
    P.S. By default, the remove duplicate setting is turned OFF. You can choose to turn it ON by changing the settings to start removing duplicate emails.


  • Corrupted or unreadable data can make it impossible to interpret by our systems resulting in a mismatch between the email addresses found and the rows in your file. One example of corrupt data include using non-UTF characters that don’t register as an email address.


Processing Time

Bytesignal is capable of cleaning more than 150 Million emails per day.

It takes us about 30 to 45 minutes per 100,000 of mixed domains.

We can validate the emails even faster, but our Anti-Grey Listing Technology needs the results to be lagged by 15 minutes to offer efficient results. Having said that, there are real-time progress statistics that you can check to know the status of your verification file. The progress of your verification file will be updated every ten seconds.

You can check the Bulk Verification page to keep a tab on the progress.

You will receive an email once your entire list is validated, allowing you to download the reports from your Bytesignal account.

P.S. If you want faster results, consider separating the ESP domains such as Gmail, Yahoo, Hotmail, etc. in a different file as these domains are much quicker to process than the smaller ones.

Downloading the results

Once the email validation status of your file is completed you can download the results by clicking on the Download Report button.


Once you click on the Download Report button you will find three options:

  • Valid Only
  • Full Report
  • Custom Report


  • Valid Only To download only the valid ones, you can tick the Valid Only box and download the report. Bytesignal’s 99% Deliverability Guarantee covers deliverable results.


  • Full Report If you want a detailed report, you can select the Full Report box which offers all the email list details including your verification results.


  • Custom Report If you want to download only a part of your results, such as Catch-All emails, Spam Trap emails or Invalid emails, then you can select a Custom Report.


Understanding results

  • Valid

Valid emails are the ones the Bytesignal system determines are safe to email to. They have a very low bounce rate of less than 1%.
There are a couple of reasons your emails can bounce:

  • When your IP might be blacklisted where our IP was not.
  • When the email address exists but is accepting emails from people added in the contact lists alone.
  • When you get a limit on the emails, you can send to a specific domain every hour. You can look at the SMTP bounce codes to know the reason for email bounces.


  • Invalid

These are the emails that we determine as invalid for any of the following reasons:

  • It contains domains that don’t accept incoming traffic but only send emails
  • Emails with syntax errors
  • Mailbox not found
  • Non-routable IP addresses
  • Email quota exceeded
  • No DNS records
  • Typing errors in the email address


Our results are 99% Accurate, and we recommend you Do Not use this list to send emails.

  • Catch-All

Some domains accept all incoming emails sent to them, including the invalid ones. This makes it difficult to validate these emails, and so, requires sending a real email and waiting for it to bounce. Once the email is sent, it may either get silently discarded by the recipient server or the server may send a bounce message. In either case, we do not guarantee the user will receive the email in their inbox.

When you send an email to a catch-all domain, it can lower your open rates or increase your bounce rates. Hence, some level of caution is always advised when sending to catch-all domains.

Bytesignal DOES NOT recommend using the following list to send emails.

  • Spam Trap

Spam Traps can identify and monitor spam emails. They can get your domain name or IP address blacklisted thereby negatively impacting your email deliverability and sending reputation. We have the right technology to identify a lot of spam trap email addresses, preventing them from getting added in your contact list. We strictly advise you to NEVER USE this list for sending emails.

  • Do Not Mail

These are the emails we identify as Disposable, Toxic, Grey-Listed (emails that didn’t respond to our verification system twice in a row while validating the email address), Harmful and Bot-Created. We separate these into a different file called Do Not Mail. It is recommended that you DO NOT use this file for sending emails.

  • Role-Based

These are email addresses that belong to a Specific Department, or Designation or a Group of Recipients. For example, admin@, leads@, sales@, help@, and more. Typically, they are not intended for personal use. Sending an email on a role-based email address can result in a decreased open rate and is generally not recommended. All the emails that we flag as Role-Based are valid emails and have been validated. However, we DO NOT recommend using this list to send emails.

Understanding the Report

The Executive Overview Report gives you a comprehensive view of your data. It will be categorized into two sub-sections:

  • Top Domains: These will give you a percentage-wise breakup of the top 11 domains in your email list
  • Validation Results: This offers the entire statistics of different validation results of your completed file.


Data Retention Policy / Deleting Data

Your results are stored with us for only 30 days and will delete them from our systems automatically.

  • Before deletion, you will be alerted three days in advance by an email reminding you to store your results if you wish.
  • If you want to turn off these notifications, you can go to your settings on the left-hand menu and uncheck the notification option.
  • Additionally, you can delete your files on your own too from the dashboard whenever you want.

All the files you upload/download on/from our system are encrypted. We ensure that your data is safe at all times and don’t store your personal data in our database.

When you delete the files yourself, or it gets deleted from our end automatically after the expiry period, the summary data is also deleted from our system.

Potential issues

We are constantly working on our algorithms to offer the best Email Validation Service, Data Append features, Catch-All, Abuse & Spam Trap Detection, and Toxic, Disposable Emails Detection in the market.

In the case you experience an abnormally high bounce rate of over 1% for emails marked valid, please bring it to our attention right away.

To do so, you can send us an email at [email protected] along with the SMTP logs. Please remember to attach the SMTP logs so we can determine the reason the emails are getting bounced. There can be many reasons for it, including the content of the email you send. Thus, it would help us to look into the logs and know the right reason for the issue.

Our guarantee

Bytesignal guarantees that after using our services, not more than 1% of your emails will bounce. Should it exceed 1% after sending only valid emails, we will refund you the difference.

Here is the criteria you must fulfill to meet this guarantee:

  • Your list must have at least 1000 unique email addresses.
  • Bytesignal must have cleaned the list within 72 hours of being mailed to.
  • The guarantee only extends to valid email addresses and excludes the ones marked as invalid, spam traps, catch-all and do not mail.
  • Emails sent through free-mail providers have a high propensity of false bounces and thus not covered by our guarantee. These include providers such as Outlook, Gmail, Yahoo and more.
  • Email addresses that bounce must be marked invalid.
  • Bounces caused due to sender reputation, internal technical issues and other similar technicalities will not be covered under guarantee.


If you want to submit a case, here’s how you can do it:

Send us an email at [email protected]. Please don’t forget to mention the following details:

  • Your Job ID processed through us
  • The time and date of sending
  • The categories sent to (invalid, valid, spam traps, etc.)