I want to create a module that intercepts all outgoing emails and changes the subject.
Is this possible? Is there an event that is dispatched whenever a mail is sent?
If not, how can I override the order email / invoice email address at least?
thanks in advance!
All the emails are sent via 'core/email_template' model, so you may override its method called getTemplateSubject() for such purpose. Unfortunately there are no events dispatched.