The mail merge that sent the wrong details to the wrong person
The worst mail merge mistake doesn't look like a mistake. Every email is well formed and every name is spelled right — but the balance, the appointment time or the exam result belongs to someone else.
How it happens
Someone selects one column — the names, say — and sorts it A–Z. Google Sheets™ asks whether to expand the selection; they click past it. Now the names are in alphabetical order and everything else is not. The same thing happens when a column is pasted in from another export in a different order, or when rows are deleted from one column only.
From then on, each row pairs one person's name with another person's address and details. If the template says Dear {{Name}}, your balance is {{Balance}}, it is now telling one person someone else's balance. For a school, a clinic or a finance team that is a data breach, not just an awkward email.
Signs your list is misaligned
- A column is perfectly sorted while its neighbours are not.
- The name in an email address (
priya.patel@…) doesn't match the name in the row (Tom Price) — for a run of rows, not just one. - Version history shows a sort on a single column.
How to check by hand
- Spot-check ten rows spread through the list: does the name match the address?
- Look at File → Version history for a recent sort, and restore the version before it if you find one.
- If the list came from several exports, join them on a key (an email or ID) rather than pasting side by side.
Let a checker look at every row
Mail Merge Pre-flight Check compares names with addresses across the whole list and flags a run of rows that look shifted, showing its evidence on the card. It allows for nicknames, shared inboxes like accounts@ and family addresses, and it never changes your data. Checking is free.
Mail Merge Pre-flight Check checks your list and template in one click. Checking is free.
Mail Merge Pre-flight Check is not affiliated with Google or with any merge tool named on this page. Names are used only to identify them.