This extension is maintained by MyOutDesk

Gmail Auto-Bcc Chrome Extension

This extension auto populates the CC, BCC fields within gmail based on user-supplied rules.

Installation

Load unpacked extension point it to the dist folder

npm install
npm run dev

Gmail is a mess UI wise, so this is the approach we took:

Extension runs on page and attaches a MutationObserver to scan for DOM changes that add a new form with the class bAs
When we see that form show up, we know that a new compose or reply has been initiated
Locate, by examining random UI hints (using aria-label, for instance) the parents of TO, CC, and BCC within that new form
Find existing "cards" (aka recipients in any field) which already exist in those fields. This is because they are clickable, hover-able, etc.
Attach mutation observers to watch for new inputs \ new cards which may show up in the To field
Populate the CC, BCC based on the existing "To" field, or populate when a recipient is added

Hopefully this provides a long-lasting solution without much pain. You can review the entire code here

You can build this extension by running:

npm run build