| Letter | Meaning | Suggested Action |
| R | Reputation Threat | Valid email addresses in which Webbula detects a potential reputation threat. I.E. Blocklisting/Blacklists, Malicious Moles, Spam Traps. Suppress these addresses. |
| F | Fraud Threat | Valid emails addresses, but posses a fraud risk, these addresses include bots and shadow domains. Suppress these addresses. |
| D | Delivery Threat | Invalid email addresses that will affect deliverability rates. I.E. improper RFC rules, domain rules, duplicates, temporary emails. Suppress these addresses. |
| C | Conversion Threat | Valid emails, but may not convert, such as school or military addresses. Use caution. |
| B | Beta Threat | Filters under development by our team. For experience users only. |
| G | Good-to-Go | No threats detected and are ready to email. |
| I | Invalid | An email address that has improper formatting. Suppress these addresses. |
| V | Valid | Email addresses that are deliverable. Threat emails are sorted based on your profile settings. |
| U | Unknown | Email addresses that have successfully passed Webbula's hygiene test, but could not determine the validity of the email address. You can send to these emails, and sprinkle these throughout a list if concerned for deliverability rates. |
| S | Social Media | Indicates the email address is associated with an active social media profile, identified through image-sharing, status/update, or payment-linked social network ecosystems. |
These letters or email flags listed in the report stand for threat categories, and they indicate which types of threats (and how many) pose threats to your organization. Spelled out, the letters are short for: Reputation, Fraud, Delivery, Conversion, Beta, Good to Go, Invalid, Valid, Unknown.
Webbula always recommends that the (RFD) Reputation, Fraud, and Delivery flagged emails are suppressed. For example, a spammer email is a legitimate address that poses a fraud threat, but it is still a valid email. C stands for Conversion, and Webbula recommends that you make the best decision to send or not send based upon your risk tolerance. For example, these emails may be associated with a school or military, and they may pose a conversion threat even though they are still valid addresses.
What's the difference between Unknown, Accept-All, and Catch-All?
These terms are often confused, but they describe different things.
Unknown means ZUVO Protect could not conclusively determine whether an address is Valid or Invalid during real-time verification. The domain is running email services, but its configuration prevents a definitive answer without actually sending a message. Unknown rates are common for business email addresses and typically range from 10–60%, with 20–30% being most common.
Accept-All is a status used by some verification-only vendors. It describes a domain configured to respond "yes" to every address query — whether or not that address actually exists. Vendors that rely solely on this kind of real-time query, without deeper verification, may misreport plainly invalid addresses as valid.
Catch-All refers to a mailbox an organization sets up to receive messages sent to any address at their domain, including misspelled or nonexistent ones — a safety net so valid mail isn't lost to a typo. Catch-All is a mail server configuration; Accept-All is a verification result. The two are sometimes used interchangeably, but they aren't the same thing.
|
Good to Know ZUVO Protect's Unknown result reflects a genuine verification limit — not a guess. Sending strategy for Unknown records is covered in "Acting on Your Results." |
Why would a valid, deliverable address get flagged Invalid?
This is known as a false negative — a deliverable address incorrectly identified as Invalid. It's most common with business domains, and can happen for a few reasons:
- Temporary outages on the receiving mail server
- Recent DNS changes that haven't fully propagated
- Complex graylisting configurations
- Slow server response times, particularly on business domains
No email verification service can achieve 100% accuracy — all providers are ultimately at the mercy of how the internet's mail servers are configured and respond in the moment a check is performed.
If you're confident a specific address is Valid despite an Invalid flag, the decision to include it in your sends is yours to make. Keep in mind that sending broadly to addresses flagged Invalid — rather than making a targeted, confident exception — can still create real deliverability and reputation issues.
Hygiene flags for an email may change over time because every time you process a file, Webbula processes the data in real-time. This means that we follow the lifecycle of an email from birth to death and everywhere in between. The flags you receive that are different than a past result may be due to the change in activity of an email since the file was last processed. This ensures that you receive the most current and accurate data possible.Webbula recommends that you overlay the ZUVO Protect flag results with your own data. This will improve your data to assist your decision-making process.