Weird Problem: Postfix related or system related?

[antitrustworthy]

I recently reinstalled my mail/web server. When I did, i copied all important config files and put them back on when I was done. Everything seems to be working except one thing: I cant send mail. Recieving is fine, but when I send, I get the following error in the log:

Aug 18 16:55:27 server postfix/smtpd[4597]: connect from server.yourcomputerbytes.com[192.168.1.100]
Aug 18 16:55:27 server postfix/smtpd[4597]: 9587547082: client=server.yourcomputerbytes.com[192.168.1.100]
Aug 18 16:55:27 server postfix/cleanup[986]: 9587547082: message-id=<4547.141.165.209.192.1092866118.squirrel@141.165.209.192>
Aug 18 16:55:27 server postfix/qmgr[21274]: 9587547082: from=<apache@_HOSTNAME_>, size=1505, nrcpt=1 (queue active)
Aug 18 16:55:27 server postfix/smtpd[4597]: disconnect from server.yourcomputerbytes.com[192.168.1.100]
Aug 18 16:55:27 server postfix/smtp[21276]: E794247081: to=<antitrustworthy@elitemail.org>, relay=192.168.1.100[192.168.1.100], delay=9, status=sent (250 2.6.0 Ok, id=16915-01, from MTA: 250 Ok: queued as 9587547082)
Aug 18 16:55:30 server postfix/smtp[28873]: 9587547082: to=<antitrustworthy@elitemail.org>, relay=smtp.us.messagingengine.com[66.111.4.31], delay=3, status=bounced (host smtp.us.messagingengine.com[66.111.4.31] said: 504 <apache@_HOSTNAME_>: Sender address rejected: need fully-qualified address (in reply to RCPT TO command))
Aug 18 16:55:30 server postfix/cleanup[986]: 50C8A47081: message-id=<20040818215530.50C8A47081@server.yourcomputerbytes.com>
Aug 18 16:55:30 server postfix/qmgr[21274]: 50C8A47081: from=<>, size=3550, nrcpt=1 (queue active)
Aug 18 16:55:31 server postfix/smtp[28873]: 50C8A47081: to=<apache@_HOSTNAME_>, relay=none, delay=1, status=bounced (Name service error for name=_hostname_ type=A: Host not found)

My setup is as follows:

Postfix with amavisd-new, courier-imap, clamav, spamassassin, procmail, and squirrelmail

I will be happy to post config files if it is necessary. Just let me know.

Thanks,

Matt

[antitrustworthy]

I fixed it. I had changed around a few things earlier, but apparently they didnt take effect until I remerged postfix. It's all good now.