New email neither receiving nor sending


I have just set up a new email account, but it neither receives nor sends any messages.

I can log into Squirrel Mail, but there are no test messages received which I sent from my other user (same domain!). I also sent a test email to myself from this new account. I can see it in Squirrel Mail’s outbox, but it has not arrived at its destination.

Any idea what may be wrong. It’s not that this is my first time I’m adding new emails. Never had this before, though.