Gmail™ mail merge fields not working? Check your column headers

By Paul Kemp · Published 24 September 2026 · Updated 2 October 2026

You write Dear {{First Name}}, run the merge, and the email arrives saying exactly that — braces and all — or with a gap where the name should be. The merge tool could not find a column called First Name. Usually the header is spelled differently in a way you can't see.

The usual culprits

A trailing space. First Name with a space at the end is a different header. It is invisible in the cell.
A typo in the template. {{Frist Name}} reads correctly at a glance.
Different wording. The template says {{Firstname}}, the sheet says First name. Some tools ignore case, some ignore spaces, some ignore neither.
The header is not in row 1. Exports often put a title above the table. Most tools read row 1 as the headers.
Two columns share a name. The tool picks one, not necessarily the one you meant.
Smart quotes or pasted formatting inside the braces when the template was drafted in a word processor.

How to check by hand

Click each header you use and look at the formula bar: put the cursor at the end to see trailing spaces.
Copy the header text and paste it into the template tag, rather than retyping it.
Make sure the table starts in A1, with no merged header cells.
Send the merge to yourself first, with the tool's test or preview option.

Ninety seconds: what Mail Merge Pre-flight Check catches before you send.

Or let a checker compare them

Mail Merge Pre-flight Check lists every tag in your template, matches it against your headers the way your merge tool does, and flags tags with no column and near misses with a suggested fix — before anything is sent. Checking is free.

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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.