Pass in an email message with HTML part and this script will open your browser for you to view it. For text mail user agents like mutt.

$ viewhtmlmsg --help
usage: viewhtmlmsg [-h] [-s] [-w WAIT] [-b APP] [--fork]

viewhtml - unpack html message and display with browser

optional arguments:
  -h, --help            show this help message and exit
  -s, --safe            view html w/o loading remote files
  -w WAIT, --wait WAIT  remove temporary files after WAIT seconds (0 for keeping files)
  -b APP, --browser APP
                        prefer browser APP over $BROWSER environment
  --fork                fork immediately

This is a derived work of the viewhtmlmsg script from the muttils project.