Zimlet to Pre-Process Email

[java_macchiato]

I would like to create a Zimlet that does some processing on an email before it is sent. Basically, when the user clicks the Send button, the Zimlet would need to do some action on the email text before the standard "Send" action is completed. I've made quite a few Zimlets now, so I'm no longer a rookie, but this has me stumped.

A lot of command-driven frameworks I've worked with allow you to add listeners to events. For example, you could subscribe to the "onSend" command and implement a doBeforeSend method. Can I do anything like this with Zimbra?