# Mail merge

*Marketing*. A process that generates customized email messages from a generic template and store of contact data.

* The original document, or [*template*][], contains static text with placeholders for substitutions for data like names, addresses, emails, or other unique information.
* Most data that populates these placeholders comes from a database, spreadsheet, or CSV file.
* The column headings in a spreadsheet or field names in a database map to the template's placeholder labels.
* During the merge, the process replaces placeholders with the data from a database record or row and creates a customized email.

Mail merges can also create customized letters and documents using a word processor and spreadsheet.

[*template*]: /docs/glossary/transactional-email-templates