Supply a YAML file as configuration, as in this example. Via the document ID and SQL query, point at data in a Grist document.

Optionally, it inserts or update records in the database based on the data processed.

pip install grist-mailmerge

or

pipx install grist-mailmerge

grist-mailmerge --dry-run config.yml
grist-mailmerge config.yml

See the this example and the command line help.