Flag Disposable Emails in a Excel Using Kickbox

The Scenario

You're a SaaS marketing coordinator. Free-trial signups have been climbing for three months — which should feel like good news. But open rates have been sliding, and your deliverability consultant flagged that 12–15% of the addresses on your 1,500-row signup workbook look like throwaway addresses from services like Mailinator, Guerrilla Mail, and Temp-Mail.

You pull up the 'Signups' worksheet. Column A is email. Columns B through E are signup date, plan tier, UTM source, and country. Nobody has ever run a disposable-domain check on this list. Every one of those fake signups is inflating your active-user count and dragging down every engagement metric you report.

The bad version:

• Google "disposable email checker," find a tool that lets you paste addresses one by one, and start working through column A.
• Get through 40 rows, realize this is going to take three hours for 1,500 addresses, and look for a bulk option.
• Find a CSV upload tool, export the workbook, wait for results, download the output, and try to figure out which result rows map to which original rows — because the tool sorted alphabetically and your workbook is sorted by signup date.

Deliverability doesn't fix itself while you're resorting CSVs.

The Easy Way: One Prompt in SheetXAI

SheetXAI is an AI agent that lives inside your Excel workbook. It reads the data and through its built-in Kickbox integration it can run Kickbox's disposable-email check on every row and flag the bad ones — no exports, no downloads, no column-matching.

Check every email in column A against Kickbox's disposable-email endpoint and put TRUE or FALSE in column B, then highlight all TRUE rows in red

What You Get

• Column B receives TRUE for any address Kickbox identifies as a disposable domain, FALSE for everything else.
• All TRUE rows are highlighted in red so you can see the extent of the problem at a glance.
• Your original columns C through E are untouched.
• Rows where the API check returns an error get flagged separately so you can decide whether to re-run or exclude them.

What If the Data Is Not Quite Ready

Signups came in with the email mixed with a display name (e.g., "Jane Doe <jane@mailinator.com>")

Some form integrations write full contact strings rather than bare email addresses.

Extract the email address from each cell in column A (stripping any name prefix and angle brackets), then check each extracted address with Kickbox's disposable-email endpoint and write TRUE or FALSE to column B

You want to move flagged rows to a quarantine worksheet instead of just flagging them

Scan column A in the 'Signups' worksheet for disposable emails using Kickbox, move all flagged rows to a new worksheet called 'Disposable', and leave the clean rows in place

The list has duplicates and you only want to check each address once

Running duplicate addresses through Kickbox wastes API credits.

Deduplicate column A by email address, check each unique address with Kickbox's disposable-email endpoint, write TRUE or FALSE to column B for each unique row, and mark duplicate rows in column B as 'DUPLICATE'

Full triage: deduplicate, flag disposable, flag undeliverable, and write a summary count

Deduplicate column A, run Kickbox on each unique address checking both the disposable flag and the deliverability result, write the disposable flag in column B and the result code in column C, then add a summary table at the bottom counting Deliverable, Risky, Undeliverable, Disposable, and Duplicate rows

One prompt produces the full audit your deliverability consultant asked for.

Try It

Get the 7-day free trial of SheetXAI and open your signup workbook, then ask it to flag all disposable addresses in column A using Kickbox. From there, check out the deliverability tiering spoke or head back to the Kickbox hub for the full method breakdown.