Redmine

I'm not sure if this is a Redmine bug or a bug with the System Notification plugin, or even it is restricted to system notifications. Many users receive normal emails when I send a system notification, but others receive emails with a subject line and a blank body. Some people receive a blank email body, but with the html markup as an attachment.

Ruby version 1.8.7 (i486-linux)
RubyGems version 1.3.7
Rack version 1.1
Rails version 2.3.5
Active Record version 2.3.5
Active Resource version 2.3.5
Action Mailer version 2.3.5
Active Support version 2.3.5
Edge Rails revision unknown
Application root /usr/share/redmine
Environment production
Database adapter mysql
Database schema version 20100819172912

About your Redmine plugins
SCM Creator 0.2.0
Redmine System Notification plugin 0.2.0