Testing for the first time

Hi this is a new topic because the last one was before the installation have completed, I have Ubuntu server 12.04 with iRedMail 0.8.5 working for the first time.
After adding new users: user1 and user2, i sent a message from user1 to user2 and visa versa from the roundcube interface, but no thing in the inbox for each, and also the message: "message sent successfully" appears!! , any idea?.