You've uploaded your email list, run it through verification and received your results. So, what should you look at first?
For many marketing teams, the obvious starting point is how many addresses have passed verification. It's a useful figure, but there's more information in the results that can help you understand the quality of your data.
A list might contain a high proportion of valid addresses alongside catch-all domains, disposable email addresses or contacts that couldn't be verified conclusively. Understanding these differences can help you decide which addresses to remove, which need further investigation and where your data collection processes might need attention.
Good bulk email verification software should make this information easy to access and understand.
Here are seven areas worth reviewing before your next campaign, and how to use the results to make better decisions about your email data.
The first figure most marketers look for is the proportion of addresses that have passed verification.
Your valid address percentage gives you a starting point for understanding list quality. It shows how many of the addresses checked have returned a successful verification result.
For example, if you verify 20,000 unique addresses and 18,000 return a valid result, that's a 90% valid address rate.
It's a useful figure to monitor, particularly if you're regularly checking the same database or comparing lists from different sources.
However, a valid result doesn't guarantee inbox placement or engagement. Your sender reputation, email authentication and other factors still influence email deliverability.
In Email Hippo CORE, successfully verified addresses receive an Ok result, with the secondary status Success.
What to look for: Compare your valid address percentage across verification runs. If it's declining, investigate how contacts are entering your database and how long they're remaining there without being checked.
Invalid addresses are one of the more straightforward results to act on, but it's worth understanding why an address has failed verification.
An address might fail because the domain doesn't exist, the formatting is incorrect or the mail server has returned an error.
Some problems are permanent. Others may be temporary.
For example, an address containing two @ symbols is incorrectly formatted and needs correcting or removing. A full mailbox, however, may become available again, while a mail server fault could be resolved without any change to the address itself.
This is why the information behind an invalid result can be just as useful as the overall number.
For marketers carrying out regular email list cleaning, understanding these reasons can also help identify problems with how data is collected.
CORE uses the primary result Bad for addresses that fail verification. It also provides a secondary status explaining the reason, which might include:
Rather than treating every failed address in exactly the same way, you can use this information to decide what needs removing, correcting or checking again.
What to look for: Review both the number of invalid results and the reasons behind them. Exclude addresses with confirmed permanent problems from your sendable list, and consider rechecking those affected by potentially temporary issues.
An Unverifiable result means the verification service couldn't reach a conclusive decision about an address.
It doesn't automatically mean the address is invalid.
This distinction is particularly important for B2B marketing teams, where corporate mail servers may use security measures that make individual addresses difficult to verify.
For example, some servers use greylisting, which temporarily delays connections. Others accept messages for any address on their domain, making it difficult to establish whether a particular mailbox exists.
Imagine you've uploaded a list containing 30,000 unique contacts and 3,000 return as Unverifiable.
Removing them all could mean unnecessarily excluding legitimate business contacts. Equally, sending to every address without considering the uncertainty could introduce avoidable risk.
The additional information returned by your verification service can help you decide what to do with these contacts.
Email Hippo CORE provides secondary statuses for Unverifiable results, including:
These explain why verification couldn't reach a conclusive result, helping you understand whether a further check or a different approach might be appropriate.
What to look for: Review why addresses are Unverifiable before deciding what to do with them. Consider their source, previous engagement and whether another verification attempt might be worthwhile or if you need to manage your sending to those addresses more closely
Catch-all mail servers accept incoming email for a domain without necessarily confirming whether the individual mailbox exists.
They're particularly relevant to B2B email verification because some businesses configure their email systems this way.
For example, a company's mail server might accept messages addressed to several variations of an employee's name. However, that doesn't necessarily mean every variation will reach the intended person.
During verification, a catch-all server can prevent the service from establishing whether the individual mailbox exists.
You can use the number of catch-all results to calculate how much of your list falls into this category.
Catch-all addresses aren't automatically bad, but they do introduce uncertainty. If a large proportion of your contacts are associated with catch-all domains, it's worth understanding where those addresses came from and whether you have any previous engagement data.
In CORE, these addresses are identified under the secondary status Unverifiable / Server is catch all.
What to look for: Consider reviewing catch-all addresses separately from confirmed valid contacts. Previous engagement and the reliability of the data source may help you decide whether they're appropriate to include in a campaign.
Disposable email addresses are often used when someone wants temporary access to a service without sharing their regular email address.
For both B2C and B2B marketers, they're worth identifying, particularly when measuring the quality of leads generated through website forms, gated content and other lead generation campaigns.
Suppose your business offers an industry report in exchange for an email address. If a significant proportion of registrations use disposable email services, it could be worth investigating how those leads are being collected and qualified.
Disposable email detection helps identify addresses associated with known temporary email services. By comparing the number identified against the total addresses checked, you can calculate their proportion of your list.
This information can be useful beyond the immediate campaign. If disposable addresses consistently appear in leads from a particular source, it may indicate an issue with your data collection process.
Email Hippo CORE identifies known disposable email address domains using the secondary status Unverifiable / Domain is well known DEA.
What to look for: Review disposable address results alongside your lead sources. Consider excluding identified disposable addresses from ongoing marketing campaigns and investigating where they're entering your database.
For more information, read our guide to identifying disposable email addresses.
Spam traps are email addresses used by anti-spam organisations and mailbox providers to identify potentially problematic sending practices.
They can appear in marketing databases through outdated contact information, poor data sourcing or lists that haven't been maintained properly.
Sending to spam traps can affect your sender reputation and may contribute to blocklisting.
Some email verification services return warnings about addresses that may be associated with spam traps. These should be treated as potential indicators rather than definitive confirmation.
No verification service can guarantee that it will identify every spam trap.
Nevertheless, finding addresses flagged as possible spam traps gives your team an opportunity to investigate before sending.
For marketers working with large databases, repeated warnings might also highlight wider issues with data sourcing or list maintenance.
CORE can return the secondary status Bad / Possible spam trap detected, allowing you to identify addresses carrying this warning.
What to look for: Exclude addresses flagged as possible spam traps from your campaigns and review how they entered your database. If you're regularly finding these results, consider whether your data collection and maintenance processes need attention.
Read more about spam trap email addresses and how verification can help.
Duplicates can easily build up in a marketing database, particularly when contacts are imported from several sources.
Someone might download a resource, attend a webinar and later appear on a list imported by the sales team. Depending on how your systems manage that information, the same email address could appear multiple times.
Comparing the total records in an uploaded file with the number of unique addresses can help you understand how much duplication exists.
While many email marketing platforms have their own duplicate management processes, identifying repeated addresses during bulk verification provides another opportunity to review your database.
For marketing teams regularly importing and verifying large lists, this can also have a cost implication.
Email Hippo CORE's file reporting shows the number of records uploaded, unique email addresses, duplicate email addresses and invalid email addresses.
CORE only charges for unique email addresses within an uploaded file. If the same address appears more than once, you're not charged for verifying each duplicate occurrence.
However, duplicates should still be addressed in your CRM or marketing platform. Verification can highlight the issue, but your underlying data management processes determine whether it keeps happening.
What to look for: Compare your uploaded records against the number of unique addresses. If duplication is common, investigate how contacts are being imported and managed between systems.
Understanding individual results is useful, but the next step is deciding what to do with them.
After verifying a large B2B database, you might find that most addresses have passed, a smaller proportion have failed and another group couldn't be conclusively verified.
Rather than applying the same decision to the entire list, you can review these groups separately.
For example, addresses that pass verification may be suitable to include in your campaign, while those with confirmed permanent errors should be excluded. Addresses that couldn't be verified conclusively may need further investigation, depending on their history and the reason for the result.
This is where the reporting and download options offered by your bulk email verification software become particularly useful.
With Email Hippo CORE, you can download results according to their primary verification status:
The results include primary and secondary verification statuses, giving you more information about why each address received its result.
For example, your marketing team could download the Ok results to prepare a campaign, review the Bad file to identify addresses requiring correction or removal, and investigate the Unverifiable results separately.
Downloading the complete file in its original order can also be useful when comparing verification results against an existing database or imported list.
CORE's dashboard provides an overview of uploaded files, including record counts and verification results, so you can review the data before downloading it.
Over time, this approach to list quality reporting can help identify patterns.
You might find that one lead generation source consistently produces more disposable addresses, or that older contact records have a higher proportion of failed verification results.
These findings can help improve how email data is collected and maintained, rather than repeatedly dealing with the same problems before every campaign.
Email Hippo CORE is designed for businesses that need to verify existing email lists, whether they're preparing a campaign or carrying out regular database maintenance.
You can upload files containing up to 500,000 email addresses, or paste smaller lists directly into the platform.
CORE performs a range of verification checks, including syntax, domain, mail server, disposable address, greylisting and catch-all detection.
Its primary and secondary verification statuses provide more detail about individual addresses, while the dashboard and download options make it easier to review and manage the results.
For B2B marketing teams, this means you can identify addresses that need removing, investigate uncertain results and prepare more reliable email data before your next send.
If you're comparing email validation services, it's worth looking beyond the number of addresses a service can process. Consider the detail it returns and whether your team can use that information to make practical decisions.
Find out more about Email Hippo CORE.
Start with the proportion of valid, invalid and unverifiable addresses. These provide an overview of list quality. Additional information about catch-all mail servers, disposable addresses and verification failures helps explain where further action may be needed.
A primary status provides the overall verification outcome, while a secondary status explains the result in more detail. For example, Email Hippo CORE uses Ok, Bad and Unverifiable as its primary results, with secondary statuses to explain why an address has passed, failed or couldn't be conclusively verified.
This depends on your verification provider. Email Hippo CORE lets you download results by primary status, including Ok, Bad and Unverifiable. You can also download the complete results file in its original order.
No. Bulk email verification helps identify invalid and potentially risky addresses before sending, which can reduce avoidable bounces and support good list hygiene. However, inbox placement also depends on factors such as email authentication, sender reputation, content and recipient engagement.