The Scenario
You're the onboarding engineer at a transactional email provider. Forty new customers just finished signup. Before you flip the sending switch on any of them, you need to confirm SMTP connectivity, TLS availability, and DNS alignment — and you need it documented in the onboarding workbook because your team lead reviews every new account before activation.
The customer success team already sent the "you're almost live" emails. The clock is running.
The bad version:
- Open MX Toolbox, go to SMTP Lookup, paste the first domain, wait for the connectivity test to complete, read through the banner response, note whether TLS is supported, go back to the workbook, enter those values into the row.
- Repeat for 39 more domains, hoping you don't mix up which result belonged to which row when the tab order gets confusing.
- End up with a workbook that has some columns filled in inconsistently because row 12 had a connection failure and you had to figure out how to record that.
Forty domains before you can activate a single account. Every manual lookup is time your new customers aren't sending.
The Easy Way: One Prompt in SheetXAI
SheetXAI is an AI agent that lives inside your Excel workbook. It reads your onboarding tracker and through its built-in MX Toolbox integration runs SMTP tests for every domain in the list, writing connection status, TLS availability, and failure reasons directly into the workbook.
Use MXToolbox SMTP lookup on every domain in my Excel workbook and fill in whether the SMTP test passed, the banner response, and TLS availability in the next three columns
What You Get
- Column B: whether the SMTP test passed — PASS, FAIL, or TIMEOUT
- Column C: the SMTP banner response from the server
- Column D: TLS availability — SUPPORTED or NOT-SUPPORTED — based on the test result
- Domains that fail show their reason immediately without any additional lookup
What If the Data Is Not Quite Ready
Need to capture failure reasons separately from pass/fail
Run SMTP tests via MXToolbox for all domains in column A, write PASS or FAIL in column B, the banner response in column C, TLS availability in column D, and any specific failure reason in column E — leave column E blank for domains that passed
Some domains have custom SMTP ports in a separate column
For each domain in column A, check column B for a custom SMTP port — if one is specified, include it in the MXToolbox SMTP test; otherwise use the default port. Write SMTP test result, banner, and TLS availability into columns C, D, E
TLS failures need to be escalated separately from connection failures
Run SMTP tests for all domains in column A using MXToolbox, write overall status in column B, and split results into column C for TLS-specific failures and column D for connection-level failures — mark column E as ACTIVATE, NEEDS-TLS-FIX, or UNREACHABLE based on which failure type applies
Full activation readiness check in one shot
For each domain in column A, deduplicate first, then run a MXToolbox SMTP test, write test result, banner response, and TLS support into columns B, C, D, and add an ACTIVATE or HOLD label in column E — ACTIVATE if both connection and TLS passed, HOLD otherwise
One prompt, activation queue ready. No more switching between tabs for every new account.
Try It
Get the 7-day free trial of SheetXAI and open your new customer onboarding workbook, then ask it to run SMTP tests across column A. Related: Bulk Email Deliverability Audit or the MX Toolbox overview for Excel.