Business Email Appending


We are the leading business email appender globally.


The top 5 business list providers in the world all agree on one thing -- ListK is the Gold Standard of business email appending. We append a higher rate of emails at a higher accuracy than any other business email appender.

This is why we are the #1 business email appender globally. Whenever compared to others our append rates are usually double the competition. We use a special Email DNA Technology that allows us to determine emails faster and better than any other firm.

  • Double the append rate of the next best competitors.
  • Better accuracy in verifying the emails are active before delivery.
  • 100% Satisfaction on every email we deliver or you don't pay for it.

Whitepaper on B2B Appending (pdf)


Trusted by the Largest List Owners and Brokers in the Industry.


Quality Guaranteed! ListK leads the marketplace in quality, deliverability and data security. Your source data is in good hands and will never be compromised. Why risk it with a company who is brokering the append? We back all of our email appends with a money-back guarantee. We only add true B2B addresses - never consumer emails.

Will I Get Better Results? Our append quality is twice as high as the nearest competitor and we consistently prove deliverability rates of over 90%. We fully verify EVERY email we return to our customers using our SmartSender Verification System. We guarantee our service - we make good or your money back. It is as simple as that.

Our proprietary process adds fresh email using search technology - not by matching from an existing, tired list or an offshore data shop. We only add true B2B addresses - never consumer ones.


Our Process.


How is our eDNA process better? We differ from other append companies due to the fact that we do not just 'match' records from a stale database. We use a technology solution to freshly append new email data each time we start a project. Our five-step process unleashes our proprietary algorithm on your database records using known patterns for corporate domains (URLs) and using search technology to find email formats. Once our technology finds a match, we test for accuracy and append the correct email to your file.


Common Questions.


How long does the append process take?
We can process most files up to 100,000 input records in 12 - 15 business days (after all information is received and formatted properly). Larger files require a custom delivery quote. The reason it takes us a bit longer is we live verify every record to ensure deliverability and quality.

What type of email yield should you experience?
Your email yield depends on the quality and hygiene of the source file and the size of the companies in your database (propensity to have business emails that match the company's domain). Typically, you will see somewhere between a 15% - 65% yield from most files.

What is ListK's quality guarantee?
ListK stands behind all of our appended files. We consistently deliver 90%+ deliverable emails on our files and stand behind our work (see below.)

What is ListK's policy for hard bounce backs?
ListK stands behind all of its appended files. We offer a full refund for all VERIFIED hard bounces found within the first 30 days of the append being completed. Remember, bounces come in many different forms and may not have anything to do with the email address being correct. Clients send us their hard bounces, the creative used for the send and the specific platform they are using for deployment and we will approve actual hard bounces.

How much does it cost?
Our pricing on most appends is based on a pay-for-performance model plus a small fee for setting-up and processing the file. You only pay for good, verified emails we deliver. Specific price breaks are based on the size of the input file we receive.


Better Reach.  Better Targeting.  Better Results!

Contact Us