In today's technology-driven world, email marketing is surely one of the most important tools available for marketers. With its precise engagement-tracking ability and its fast, cheap, and easy-to-use nature, email marketing is expected to remain important in the coming years. Research has shown that 122 billions emails are sent per hour. But considering the enormous spam rate, how many of these emails are actually opened by users and how many of them are simply ignored? This is obviously an important question for a marketer, and there are strategies to keep metrics above a desirable level.

One such strategy is making sure the email list used is “clean.” The world changes fast, and the virtual world changes faster. People change or abandon their email addresses in a flash for various reasons (whether they change jobs, change ISPs, or simply get fed up with the spam overload and want a fresh start). Thus, it is inevitable that within the enormous volume of addresses a marketer might have, there will be some inactive addresses that are either unavailable (read: closed) or will not show any type of engagement. Such addresses fall under the “hard bounce” category, which each marketer should be very cautious about.

A high hard-bounce rate has many disadvantages. Delivery failures or delivered but unopened emails directly affect metrics such as the open rate or engagement rate. Internet service providers (ISPs) and email service providers (ESP) are openly at war with spam mails, and ESPs track open rates, click rates, and unsubscribe rates of emails. Their algorithm keeps underperforming mails out of users' inboxes. As being in a user's inbox is the first important step in email marketing, this holds a big danger. Also, a user receiving but not opening your emails might decide to send you to their spam folder at some point, which could get you labeled as a spammer and be bad for your reputation.

A clean email list has following properties:

  • Is free of syntax errors, invalid domain syntax, invalid characters, etc.
  • Does not contain generic emails such as or
  • Does not contain bogus addresses such as or
  • Is checked for domains that no longer exist and dead email addresses
  • Does not contain duplicate email addresses

You should periodically check your email list and clean it when necessary. If the email list is purchased from a service, you should make sure that the email list has the above properties.'s email lists are updated daily and checked by humans, so we guarantee that our mail lists are as clean as possible. We support our claim with a guaranteed 90% accuracy rate: If the lists you purchase from us fall short in quality, we will provide you free credits for more data.