gem letter_opener:
https://github.com/ryanb/letter_opener
Source Code for the Episode:
https://github.com/corsego/26-action-mailer/commit/24fb10065fb5c4502b15ea75d651aec8e61413e0

To fix Launchy error - run these commands in console:
export BROWSER=/dev/null
export LAUNCHY_DRY_RUN=true