Show HN: Open-source mail merge for Google Sheets

Hi everyone,

I open sourced this because mail merge Add-ons for Google Sheets have lots of power (like reading your spreadsheet, connecting to your Gmail account, etc) and I want people to know exactly what we do with those permissions. Unlike most of the other mail merge Add-ons, Mailman doesn't require permission to read your Gmail account. Also, ours has the most generous free tier of them all.