Email List Verification for Clean Leads
This task verifies every email address in your spreadsheet, marking invalid addresses and identifying catch-all domains. The result is a clean, reliable email list that boosts your outreach accuracy and reduces bounce rates.
Check every email address in my sheet, mark the invalid ones and the catch-all domains, and give me a clean list.
Runs on the Tasks plan and the Goals plan.
Who This Is For and When It Pays Off
This task is designed for businesses, marketers, and sales teams who rely on email outreach to connect with leads and customers. It is particularly useful before launching large email campaigns or sales prospecting efforts.
It pays off when you need to reduce bounce rates, protect your sender reputation, and improve deliverability. Verifying your list helps avoid wasted effort and costs from contacting invalid emails or dealing with spam traps.
- Small to large businesses preparing email marketing or cold outreach campaigns.
- Sales teams needing verified contact lists to improve conversion rates.
- Marketers who want to ensure higher email deliverability and engagement.
- Any organization seeking to maintain a clean, high-quality contact database.
How the Katteb Agent Does It, Step by Step
- The agent accesses the user's spreadsheet where the email list is stored, using the user's preferred platform like Google Sheets or Excel Online.
- It extracts all email addresses from the provided sheet for processing.
- The agent then uses third-party email verification APIs such as ZeroBounce, Hunter.io, or NeverBounce to test each address for validity and status.
- It identifies invalid emails, syntax errors, role-based addresses (e.g., admin@, support@), and flags catch-all domains where deliverability cannot be guaranteed.
- The agent marks each email entry in the sheet with validation results: valid, invalid, catch-all, or risky.
- It compiles a clean list of only the validated and safe email addresses, excluding those flagged as invalid or catch-all if requested.
- Finally, the agent delivers the updated spreadsheet with annotations and a separate clean email list file in CSV format.
What You Give the Agent Before It Starts
- A spreadsheet containing the email addresses to verify, accessible online through Google Sheets, Excel Online, or a similar platform.
- API keys or login credentials for any third-party email verification service you prefer, if applicable.
- Clear instructions on how you want invalid and catch-all addresses to be marked or handled in the result.
- Any preferences on output format, such as whether you want a separate CSV file of clean emails.
- Optional: a sample of your list or a smaller test batch for initial verification.
What a Good Result Looks Like
The task typically completes within 10 to 30 minutes depending on the size of the email list, which can be from a few hundred to several thousand addresses. Very large lists may require longer.
A good result is a spreadsheet where every email address is clearly marked as valid, invalid, catch-all, or risky, with corresponding notes.
You receive a separate clean list containing only validated, safe-to-email addresses, formatted as a CSV or a new spreadsheet tab.
Realistic performance includes identifying 2-10% invalid emails and around 5% catch-all domains, though these rates vary by list quality.
The deliverable enables higher confidence in your email outreach, with reduced bounce rates, fewer spam complaints, and better campaign ROI.
What to Expect and What Is Not Promised
Email verification depends on third-party services that may have usage limits or require API access. The agent cannot bypass platform restrictions or user-level security limits.
Verification identifies likely invalid and catch-all emails but does not guarantee 100% deliverability or inbox placement.
Some catch-all domains may still result in bounces, as email servers can accept all emails but reject some afterward.
The agent requires user sign-in permissions to access email lists and third-party APIs but does not retain or share your data beyond task completion.
Final review and approval of results remain your responsibility before importing the clean list into marketing tools.
Questions people ask
Can the agent verify emails in bulk for very large lists?
Yes, the agent can process large lists, but completion time may extend depending on list size and email verification API rate limits. Splitting very large lists might be advisable.
What are catch-all domains and why are they important?
Catch-all domains accept emails sent to any address under their domain, making it hard to distinguish valid from invalid emails. This creates uncertainty in deliverability and potential bounce rates.
Do I need to provide an email verification service API key?
Providing an API key for a preferred verification service is recommended for the best accuracy. The agent can use free or default services without keys but with possible limitations.
Will the agent store or share my email list data?
No, the agent processes your data only during the task and does not retain or distribute your email lists beyond completing the requested verification task.
How accurate is the email verification?
Verification accuracy varies with the service and list quality. It reliably detects clearly invalid emails and catch-all domains, but it cannot guarantee 100% inbox delivery due to factors outside its control.
