• Valid - We determined these addresses to be valid and safe to email. They will have a very low bounce rate of under 2%.

    If you receive bounces, it can be because your IP might be blacklisted where our IP was not. Sometimes, the email accounts exist, but they only accept mail from people in their contact lists. In other instances, you may be throttled on the number of emails you can send to a specific domain per hour. It's important to look at the SMTP Bounce codes to determine why a bounce occurred.

    • Alias_address - (valid) These email addresses act as forwarders/aliases and are not real inboxes.

      For example, if you email “,” your email is forwarded to “”

      An alias is a valid email address, and your email will not bounce. This status aims to provide more information about the email address. We can sometimes detect alias email addresses, and when we do, we let you know.

    • Leading_period_removed - (valid) If a valid email address starts with a period, '.', we will remove it so that the email address is compatible with all mailing systems.

    • Alternate - (valid) These emails are valid but likely to be secondary addresses for the users. Alternate emails are often used to sign up for accounts but do not see much engagement.

      Unlike primary email addresses, which look more formal, alternate emails usually contain numbers or special characters, e.g. Identifying alternate email addresses allows for better email list segmentation. Users with formal emails are more likely to engage with your content.

  • Invalid - These are the emails that we determined to be invalid. Please delete them from your email list. The email can be deemed invalid for various reasons, such as “mailbox not found.” The address also may not accept emails.

    Below is a list of sub_status codes to help explain some of the invalid results.

    • Does_not_accept_mail - (invalid) These domains only send mail and don't accept it.
    • Failed_syntax_check - (invalid) Emails that fail RFC syntax protocols.
    • Possible_typo - (invalid) These are emails belonging to commonly misspelled popular domains.
    • Mailbox_not_found - (invalid) These emails addresses are valid in syntax, but do not exist.
    • No_dns_entries - (invalid) These emails are valid in syntax, but the domain doesn't have any DNS records or incomplete DNS Records. Therefore, mail programs will have difficulty delivering emails to them or be entirely unsuccessful.
    • Mailbox_quota_exceeded - (invalid) These addresses exceeded their space quota and no longer accept emails (temporarily).
    • Unroutable_ip_address - (invalid) These email domains point to an unroutable IP address.
  • Catch-all - These emails are impossible to validate without sending a real email and waiting for a bounce. “Catch-all” means that the email server tells you that the email is valid, whether it's valid or invalid. If you want to email these addresses, we suggest you segment them into a catch-all group with the knowledge that some of your emails will bounce.
  • Spamtrap - These emails are believed to be spam traps , and you should not email them. We have the technology to determine if certain emails should be classified as spam traps. We don't know all the spam trap email addresses, but we know many of them.
  • Abuse - These emails are of people known to click the abuse links in emails, hence abusers or complainers. We recommend not emailing these addresses.
  • Do_not_mail - These are company emails, role-based, or simply addresses you should avoid emailing. They are broken down into 6 sub-categories "disposable," "toxic," "role_based," "role_based_catch_all," "global_suppression," and "possible_trap." Examine this file and determine if you want to email these addresses. They are valid email addresses but shouldn't be mailed in most cases.
    • Global_suppression - (do_not_mail) These emails are found in many popular global suppression lists (GSL). They consist of known ISP complainers, direct complainers, purchased addresses, domains that don't send mail, and known litigators.
    • Possible_trap - (do_not_mail) These emails contain keywords that might correlate to possible spam traps like spam@ or Examine these before deciding whether to send emails to them or not.
    • Role_based - (do_not_mail) These emails belong to a position or a group of people, like sales@ info@ and contact@. Role-based emails strongly correlate to people reporting emails sent to them as spam and abuse.
    • disposable- (do_not_mail) These email addresses are temporary and become invalid after a set period. Avoid adding disposable emails to your list to avoid future bounces.
    • toxic- (do_not_mail) These email addresses are known for abuse and spam. They may also be bot-created emails. If any of your emails possess this flag, you shouldn't email them. We also provide additional fields that you should consider before emailing.
    • Role_based_catch_all - (do_not_mail) These emails are role-based and belong to a catch_all domain.
    • mx_forward - (do_not_mail) These emails belong to domains set up to forward their MX records into one domain. Their use case is somewhat similar to disposable domains.
  • Unknown- We couldn’t validate for one reason or another. Typical cases include an offline mail server or an anti-spam email system.

    In most cases, 80% of unknowns are invalid/bad email addresses. We have the lowest "unknowns" of any email validator and don't make this statement lightly. We paid and tested email lists at over 50 validation companies to compare results.

    If you do encounter a large number of unknowns, please submit those for re-validation. Remember, you are not charged for unknown results, credits will be credited back. If you still have a large number, contact us and we will take a look and verify.

    • Antispam_system - (unknown) These emails have anti-spam systems deployed that are preventing us from validating these emails. You can submit these to us through the contact us screen.
    • Exception_occurred - (unknown) These emails caused an exception when validating. If this happens repeatedly, please let us know.
    • Failed_smtp_connection - (unknown) These emails belong to a mail server that won't allow an SMTP connection. Most of the time, these emails will end up being invalid.
    • Forcible_disconnect - (unknown) These emails belong to a mail server that disconnects immediately upon connecting. Most of the time, these emails will end up being invalid.
    • Greylisted - (unknown) Greylisting technology is temporarily preventing the validation attempt. If you resubmit these emails, they will often validate on a second pass.
    • Mail_server_did_not_respond - (unknown) These emails belong to a mail server that is not responding to mail commands. Most of the time, these emails will end up being invalid.
    • Mail_server_temporary_error - (unknown) These emails belong to a mail server returning a temporary error. Most of the time, these emails will end up being invalid.
    • Timeout_exceeded - (unknown) These emails belong to a mail server that responds slowly. Most of the time, these emails will end up being invalid.

We also provide a sub_status code to help explain some of the unknown and invalid results. Not all unknowns and invalids will have sub_status codes.

Other Fields

  • free_email- [true/false] Does the email come from a free provider?
  • mx_found- [true/false] Does the domain have an MX record?
  • mx_record- The preferred MX record of the domain
  • smtp_provider- The SMTP Provider of the email or [null] (BETA)


As a responsible email validation service, we do our best to protect your IP/Domain Mailing Reputation. Your mailing campaign succeeds when your email lands in the inbox, not the junk box.

Just eliminating bounces is the first step to a healthy IP Reputation, but there are many more steps. Read our Email Deliverability Guide.

The "Do Not Mail" Status represents one of the next steps where we identify potential emails that can cause harm to your IP/Domain Reputation.


Let's dig a little deeper into the meaning of role-based and why, but let's hear it from the mailing exports of major ESP Providers who send billions of emails daily. Click on the following links below.

There are hundreds of more links from many more large companies than the ones above explaining why. We understand that depending on your business model and industry, you might need to send messages to role-based emails. You may do this, but we must communicate the risk involved. It's your decision on which role-based emails to mail and whether the risk is worthwhile.

All emails that we flag as "Role-Based" are valid emails.