Dear,
I was requested to develop a notes client plugin to do some checking (like the spell checking) before the email sending. My basic understanding is to trap the click event of ‘send’ button/menu, but can not find how to do it…
or any other approaches? thanks a lot! 
Subject: Instead of a plugin,…
…this would be easier to do by editing the design of the mail template. You could use NotesUIDocument.SpellCheck method in the Querysend event of the Memo and other forms. It doesn’t return a code to tell you whether the spell check passed, but you could use the Timer function to determine how long the spell check took, and if it was more than a second or so, that probably means it complained to the user about something. So then you can ask them whether to go ahead and send, or cancel sending and let them edit it some more.
However, really, why not just turn on the auto spell check in the clients? I would think people would be pretty good about noticing the red underlines appearing as they type.
Subject: can I receive QuerySave event in plugin
Andre, thanks!
Actually what I want to do is not spell checking, I just use it as an analogy.
Yes, we can do something by modify the mail template, in QuerySend or QuerySave event. It would be better to be in eclipse plugin, how can I receive QuerySave event in plugin?
Subject: These core-level events are not passed to the Java API
To intercept a send document, save, etc, you would have to use Notes C API calls – read about DSAPI.