What tools are available to develop an "inmail" solution?
I want to build an application that offers an "inmail" like feature that is available in financial and other applications. 

Is there a toolset these are all based to use? Or is this all customized?

I reviewed a bit of XMPP, but that deals with Chat it seems, and not email.

I wanted to be able to send emails as well, but mostly the inmail would be used from user to user within the application domain.

Thanks in advance,
B
What tools are available to develop an "inmail" solution?
===

I want to build an application that offers an "inmail" like feature that is available in financial and other applications. 

Is there a toolset these are all based to use? Or is this all customized?

I reviewed a bit of XMPP, but that deals with Chat it seems, and not email.

I wanted to be able to send emails as well, but mostly the inmail would be used from user to user within the application domain.

Thanks in advance,
B