Since darcs 2.10 [1], the command "darcs send" no longer sends an email by default, but generates a patch bundle for later use. It is still possible to revert to the old behaviour with "darcs send --mail". We kind of acknowledged that users usually don't have (or don't want to have) an mta.
So I agree with this bug report. The darcs package should only suggest "default-mta | mail-transport-agent" instead of recommending them. Guillaume [1] http://darcs.net/Releases/2.10#user-interface
