Hello,
It really depends on why exim isn't working.
If the deamon can't start, there could be many reasons.
If it's something specific to port 25, like another smtp server running, then the send will work as DA calls the command line.
If you've made a big typo in your exim.conf, then the send won't work as the command line uses the exim.conf still.
You will always get a notice in your Message system, but if the sending program doesn't work, then the email can't get sent. (DA does not have any SMTP sending code for that case.. I'm not sure I'd want to write that code either.. ).
John