Can only send out, can't recieve

[latenightsight]

Hello,

I can only send out messages on my server, no messages are received. If you try to send a message to anyone, you get the following error:

This is an automatically generated Delivery Status Notification

Delivery to the following recipient failed permanently:

[email protected]

Technical details of permanent failure:
PERM_FAILURE: SMTP Error (state 13): 550 <[email protected]>: invalid address

However, the address IS valid. It lets me send messages to other people and it says its coming from [email protected] yet you can't respond.

I'm confused. The Qmail service is running and it seems to be fine. Any help would be appreciated!