The Scenario
You're a sales development rep at a B2B services firm. Over the past two weeks you've scraped 150 company domains from LinkedIn prospect searches — the domains are sitting in column A of a Google Sheet, one per row, with company name in column B.
Before you hand this list to the BDRs for cold outreach, you need to know which domains are actually capable of receiving email. A domain with no MX record, or one that resolves to a spam forwarding service, isn't a prospect — it's a bounce waiting to happen.
The bad version:
- Run each domain through a manual MX lookup tool one at a time, copy-paste the result into column C.
- Cross-reference a separate list of known disposable domain providers to check for forwarding flags.
- Repeat for all 150 rows while also answering Slack messages about a different campaign.
Nobody's going to spend three hours doing 150 individual lookups. So the list goes to the BDRs unchecked, the first campaign run produces a spike in bounces, and now there's a conversation about sender reputation that nobody wanted to have.
The Easy Way: One Prompt in SheetXAI
SheetXAI is an AI agent inside your Google Sheet that reads the data and talks to Mailcheck for you. Mailcheck can validate domains directly — checking MX health, disposable status, forwarding flags, domain age, and spam indicators — without needing an individual email address for each one.
For each domain in column A, call Mailcheck domain validation and write MX status, disposable flag, forwarding flag, domain age, and spam indicator into columns B through F
What You Get
- Column B: MX status — "valid", "invalid", or "no records found".
- Column C: disposable flag — TRUE or FALSE.
- Column D: forwarding flag — TRUE if the domain forwards to a known catch-all or spam relay.
- Column E: domain age — approximate registration age in years where available.
- Column F: spam indicator — TRUE if the domain appears in spam-related blocklists.
What If the Data Is Not Quite Ready
Some entries in column A have "https://" or trailing slashes — they're URLs, not clean domains
Before running Mailcheck domain validation, strip any "http://", "https://", "www.", and trailing slashes from every value in column A to get clean domain strings. Then validate each domain and write MX status, disposable flag, forwarding flag, domain age, and spam indicator into columns B through F.
I want two separate output sheets — one for domains that passed, one for those that failed
Validate all domains in column A using Mailcheck. Create a new sheet called "PASSED" with domains that have valid MX records and no spam flags — copy the company name from column B of the source sheet into column B of PASSED. Create a "FAILED" sheet with everything else, including the failure reason in column C.
Some rows have the same domain listed under multiple company names — I only want to validate each domain once
Deduplicate column A by domain before running Mailcheck validation — keep the first row for each unique domain and note how many duplicates were removed in cell A1. Then validate each unique domain and write results to columns B through F.
Score every domain, delete the clear failures, flag the borderlines, and add a handoff note for the BDRs
Validate every domain in column A with Mailcheck. Delete rows where MX status is invalid or the spam indicator is TRUE. For rows where the disposable flag is TRUE but MX is valid, highlight the row in yellow and add "Review before outreach" in column G. Then write a summary in A1: total domains, deleted, flagged for review, cleared.
One prompt handles the scoring, the cleanup, the flags, and the note — so the sheet arrives at the BDRs ready to use.
Try It
Get the 7-day free trial of SheetXAI and open the Google Sheet where your prospect domains are sitting, then ask it to run Mailcheck domain validation and split the results before the list goes anywhere near a dialer or inbox. Also see how to bulk verify lead emails before importing and the full Mailcheck integration overview.