The Scenario
You are a list manager at a media company. You run a newsletter list and a promotional list in Benchmark Email, two of your six total lists. The newsletter list has 14,000 subscribers. The promotional list has 9,000.
You are planning a re-engagement campaign that should only go to newsletter-only subscribers. To build the right audience, you need to know who appears in both lists and suppress them.
Your only tool is an Excel workbook, saved to SharePoint.
The slow version:
- Export newsletter list as CSV, paste emails into column A
- Export promotional list as CSV, paste emails into column B
- Write a COUNTIF to find overlaps
- Filter to duplicates, tag them for suppression
- The workbook has 14,000 rows and VLOOKUP is crawling and you are questioning everything.
The fast version is one prompt.
The Easy Way: One Prompt in SheetXAI
SheetXAI is an AI agent inside your Excel workbook that pulls both contact lists from Benchmark Email and runs the overlap analysis for you, without a CSV export or a formula in sight.
Open the SheetXAI sidebar and type:
Compare contacts across Benchmark Email list IDs in column A of my workbook. Find every email address that appears in more than one list. Write the overlapping emails and their list memberships into a new tab called Overlaps — one row per shared contact, with their email, name, and a comma-separated list of which lists they appear in.
SheetXAI pulls the contacts from all list IDs in column A, identifies the overlaps, and writes the results into the Overlaps tab. You get a clean suppression list without touching a CSV.
What You Get
A completed overlap analysis in the Overlaps tab:
- Email address — one row per contact who appears in more than one list
- Name — first and last name from Benchmark Email
- Lists column — comma-separated list of which list IDs each contact belongs to
- Row count — the total tells you exactly how many contacts to suppress
The suppression list is ready to use. Share the SharePoint link with the campaign team.
What If the Data Is Not Quite Ready
When you need contacts exclusive to one list
Pull all contacts from Benchmark Email list IDs in column A. Write contacts who appear only in list ID 1122 and not in list ID 3344 into a tab called Newsletter Only. Write overlapping contacts into a tab called Overlaps. One row per contact in each tab.
When email casing is inconsistent across lists
Pull contacts from all Benchmark Email list IDs in column A. Before comparing, normalize all email addresses to lowercase. Write overlapping contacts (based on normalized email) into the Overlaps tab. Write the original casing from each list into separate columns for reference.
When you need to compare all six lists at once
Pull contacts from all Benchmark Email list IDs in column A. For each unique email, write a row into the All Contacts tab showing the email, name, and a "1" or "0" in separate columns for each list ID — one column per list. That gives me a presence matrix I can filter any direction.
When you want the overlap analysis plus the campaign-ready send list
Pull contacts from Benchmark Email list IDs 1122 and 3344. Write contacts who appear in both lists into the Suppression tab — just email addresses, one per row, no header. Write contacts who appear only in list 1122 into the Send List tab with email, first name, and last name.
The pattern: describe the output you actually need — suppression file and send list — and let SheetXAI build both from the same API calls.
Try It
Get the 7-day free trial of SheetXAI and open a workbook with Benchmark Email list IDs in column A, then ask SheetXAI to run the cross-list overlap analysis. The Benchmark Email integration is included in every SheetXAI plan. See also how to export contacts for deduplication in Excel or the Benchmark Email in Excel overview.