Category Definitions



Below is a list of category definitions mailfloss uses to identify email addresses.

These emails fail syntax checking and are invalid.

These email addresses are flagged as spam accounts.

Emails are of role, such as "administrator". Although they may be valid, role emails tend to perform poorly and may affect deliverability rates.

Emails belonging to a banned keyword or domain. These are swear words and others that tend to be fake and perform poorly.

These emails are from disposable email services that are temporary. They are not worth emailing and will affect deliverability.

The domains of these emails do not have valid mx records and thus do not accept emails. They show as "illegit" in reports.

The domain for the email address is not active, is showing as parked or as available for sale. The email addresses are likely to be invalid.

The emails appear to be good but we could not verify because the domain is not responding.

Emails contain blacklisted keywords defined by the user.

Emails sent to this address have bounced in the past and can be risky to email.

These addresses have marked emails as spam in the past and are more likely to do so in the future.

These email addresses do not appear to exist based on our tests.

These addresses have been deactivated and are not able to receive incoming emails.

These addresses are over quota and are not able to receive incoming emails.

These addresses failed Microsoft Exchange testing and have the potential to hard bounce. If you have many of these addresses, it is not recommended to email them in bulk.

These email addresses at this domain look good, but any email address at this domain look good and cannot be verified completely. They show as "accept_all" in reports. For example, to fail the accept_all test, using mailfloss.com as an example, means the server returns [email protected] as a valid address but also says [email protected] is also a valid address. That means we can't know for certain that [email protected] is valid, so we fail it with the "accept_all" reason.

We skipped verification for this email address. This usually happens if you've reached your plan limits.

We’re continually refining our processes and algorithms. If you feel we’ve miscategorized some of your emails, please get in touch. If you are doing a manual floss, you can report the mistake by clicking on the “Report as Incorrect” button.