Catch-All domains always return a valid response from the SMTP service, whether the email address is actually valid or invalid. Some mail servers do this because they believe it will prevent people from harvesting real email addresses from their SMTP Server.

Some mail operators set up a catch-all address. For instance, if you mail, the mail administrator will forward that email to a "catch-all" address, like "". So they can look at all the emails sent to their mail server to see if anything important was sent to an invalid recipient.

We have found that catch-all domains get a lot more spam, because mail services have no way of telling if the email address is good or bad before sending. So spam operators just send to them, thinking someone will see the email.

Most Email validation services will just return Valid for catch-all domains without telling you. identifies these domains for you. Since we are not able to validate them, it's up to you to decide if you want to take the risk to send to these domains. We do recommend that, if you decide to send emails to catch all domains, you segment these into a different group in your mailing platform.

Now, there are 3 behaviors of catch-all email domains:
  • An non-real email address is funneled into a catch-all inbox (This does not hurt your email reputation)
  • The non-real email is bounced back, saying the user doesn't exist (This does hurt your email reputation)
  • The recipient is actually valid and the email gets delivered


First, let's explain what Abuse Emails are.

Abuse Emails are considered emails where the recipient clicks the "Spam" link often in emails sent to them. We call these high risk emails. If you email them, they might click the "Spam" link, therefore lowering your mailing reputation. Furthermore, these users contribute to causing your emails to land in the spam/bulk folders or, worse, not being delivered at all.

Now, should you send messages to Abuse Email Addresses? That's your decision. Maybe these people are really interested in what you have to say and they won't mark the mail as spam. It's your call, you know your customers better than we do and you know how you gathered these email addresses. Did you buy the list? If yes, maybe you shouldn't mail them. Are they an actual customer of your store? Then maybe you should email them. It's your decision.

How do we detect them? We have relationships in place that report this information to us. They are mostly gathered through Feedback loops or individual OPT-Out links found in people's emails.


ZeroBounce uses Zendesk as a ticketing system, to keep track of all communications with our customers. To contact us just call us, leave us a message in our support chat or visit our "Help page".

We would love to hear from you and we'll get back to you shortly!

We are in the process of setting up additional channels of communication, but for now the only way to contact us is through email support via


No, once you purchase credits, they will never expire. You can use those credits to validate your emails whenever you want. Our 24/7 customer support team is here to assist you in the process, should you need any help.