I'm not aware of any Eclipse plugins which allow it to send e-mails -- and I'm not going to bother searching the web for them, I will leave that for people who are more interested in the answer -- but let's move the post over to the Eclipse forum to see if anybody over there knows.
Why do you want Eclipse to send an email? Such functionality is usually used by background or server type applications without a user interface - such apps send emails to inform administrators of various events. But Eclipse is a GUI, and you are sitting at it asking it to do things, so I am at a loss as to what kind of event would trigger an email.
Perhaps if you described your requirements (under what conditions would an email be sent and to whom) or what you are trying to accomplish, then we could help you more.