Redmine

Recently, I want to make some customization to the emails redmine sends out.
e.g. to include some other fields in the subject when a new issue is added.

I was have the impression that i can achieve this by modifying mailer.rb after doing some research
However, what is driving me crazy is that none of the changes I made in mailer.rb seems working (just like I had done nothing, and there are not error in the production log as well)

For example,
I added “TESTMSG” to the following line in issue_add function in mailer.rb and was expecting redmine sends out a notification with that string in subject when I add a new issue. However, nothing changed after I made this change.
:subject => "[TESTMSG #{issue.project.name} - #{issue.tracker.name} ##{issue.id}] (#{issue.status.name}) #{issue.subject}"

I am using clean install of BitNami 2.3.0-1 with no plug-in at all.
Am I looking at the wrong place or did I missed anything ?
Any ideas?