The Scenario
It's Monday morning. Your inbound form collected 500 leads over the weekend and they're sitting in an Excel workbook — column A is the email address, everything else is blank. Before any of them get pushed into your CRM, your ops lead sent a Slack message: "Please validate the list first. Last time we imported a batch with half gmail addresses, the sequence performance numbers were a disaster."
You remember that batch. You remember manually scanning through it looking for obvious free-email domains. There were 400 rows and you still missed a dozen.
The bad version:
- Sort column A alphabetically and visually scan for gmail.com, yahoo.com, hotmail.com — plus the disposable domain names you happen to recognize.
- Write "FLAG" into column B for the ones you catch, knowing you're not catching all of them.
- Google "disposable email domain list," find a CSV, try to do a VLOOKUP against it that breaks on your first typo.
The ops lead is going to ask if you checked for disposables. "I tried to" is not the answer she's looking for.
The Easy Way: One Prompt in SheetXAI
SheetXAI is an AI agent that lives inside your Excel workbook. It reads your email column and runs each address through Tomba's domain validation endpoint — checking whether the domain is webmail, disposable, or legitimate business infrastructure.
Here's the prompt to use:
Scan my Excel sheet's Email column and mark any rows where the domain is a free or disposable email provider with 'FLAG' in a new Status column. For all other rows, write 'OK'.
What You Get
After running this prompt:
- The Status column contains either "FLAG" or "OK" for every row.
- Every address is checked — no visual scan, no manual sampling.
- You can filter on Status immediately: sort the flagged rows to the top or delete them before the CRM import.
- Rows where the Email column is blank are skipped.
What If the Data Is Not Quite Ready
Emails have inconsistent capitalization or extra spaces
If the inbound form didn't normalize input, you might have "John@Gmail.COM" sitting next to "sarah@acme.com". Tomba's domain check is case-insensitive, but clean data processes faster.
Trim whitespace and lowercase every email in the Email column, then check each address against Tomba's domain validation and write 'webmail', 'disposable', or 'business' into the Status column.
You want to tag free-email separately from disposable
"Webmail" covers gmail and yahoo — but your team treats those differently from throwaway domains like mailinator.com. You want a four-category output.
For every email in the Email column, classify the domain as 'business', 'free-email' (gmail, yahoo, hotmail, outlook, etc.), or 'disposable' (single-use or temporary domain). Write the classification into the Status column.
You only want to check rows where another column is blank
You've already validated some rows manually — the Reviewed column has "checked" for those rows. Skip them.
For every row where the Reviewed column is blank, check the email in the Email column against Tomba's domain validation and write the classification into the Status column. Leave rows where Reviewed already has a value untouched.
Full pipeline: deduplicate emails, validate domains, and flag high-risk rows in one pass
Remove any duplicate email addresses in the Email column (keep the first occurrence, mark duplicates in a new Duplicate column with "duplicate"). For the remaining rows, validate each email's domain via Tomba and write the classification into the Status column. Then for any row classified as 'disposable', write "DO NOT IMPORT" into the Action column.
Run cleanup and validation together — the output is import-ready.
Try It
Get the 7-day free trial of SheetXAI and open any Excel workbook with a column of inbound email addresses, then ask it to classify every domain before your next CRM import. For a related workflow, see enriching domains with professional email addresses, or the full Tomba integration overview.