email problem on comments

[Phillip Durbin]

We upgraded to bugzilla 5.06 and now emails are not sent on comments; 
email is only sent on changes to bugs (for instance new bug, add cc user 
, or change state) . This happens across all users even  if the user has 
selected all emails in their preferences . Seems like a global setting 
but I can't find one in the administrators interface  or perhaps a bug  
. Any ideas on how to debug this or configure it ? Thanks.