@apalomer, you can find the content of the emails under
src/Template/Email/html where they are listed by roles:
- AN: anonymous user
- GM: group manager
- LU: logged in user
If you change the content of the emails, it may prevent you from upgrading in the future. The best way to maintain your own version is generally to fork the source code of passbolt (on github) and pull the latest changes from passbolt for each release and merge them with your own. You will need to learn how to use Git if you wan to do this if that’s not something you’re familiar with.
I hope this helps.