Delivering locally through the Submission Server

[R. Diez]

Hi all:

I am learning Dovecot step by step. I have enabled the Submission Server, in the hope that I would not need to learn other MTAs like Postfix.

The Submission Server is very comfortable: it picks up the existing Dovecot configuration, so that you do not need to configure any user 
authentication separately. It is working fine on my test setup.

My first thought was that, if the recipient is a local mailbox, the Submission Server would not need to relay the message to any external SMTP server, 
as it could just deliver it locally. After all, it is running on the same Dovecot.

But it cannot do that, can it? Is there a work-around? I am still hoping that the mail server still works locally if the Internet connection fails. 
But I would need to learn some Postfix magic for that, would I?

Thanks in advance,
   rdiez