Guix,

See <http://issues.guix.gnu.org/49114>, which Mumi currently 
titles

  ‘guix_ lint’ should catch certificate validation exceptions

There's no underscore in the original subject.  It's also rendered 
correctly in the grey ‘mail view’ div:

  Tobias Geerinckx-Rice wrote seconds ago
  ‘guix lint’ should catch certificate validation exceptions

Perhaps due to my use of Unicode quotes.  There's nothing 
suspicious in the HTML.

Kind regards,

T G-R