Date:  Sat, 26 Sep 2009 05:38:17 +0200
From:  Michael Stauber <bq (at mark) solarspeed.net>
Subject:  [coba-e:16066] Re: relay=[127.0.0.1] [127.0.0.1], dsn=5.0.0, stat=Service unavailable
To:  coba-e (at mark) bluequartz.org
Message-Id:  <200909260538.17854.bq (at mark) solarspeed.net>
In-Reply-To:  <AD8810EE9EF545ADA54B73AE65015C9E@raqware>
References:  <893787.30366.qm (at mark) web65601.mail.ac4.yahoo.com> <AD8810EE9EF545ADA54B73AE65015C9E (at mark) raqware>
X-Mail-Count: 16066

Hi Gerald,

> I don't understand it, all worked OK, then all of a sudden localhost can't
> send email. Bad, as none of the scripts can send email.

Weird. 

See if 127.0.0.1 and "localhost" resolve:

[root@derelik web]# nslookup localhost
Server:         192.168.XX.X
Address:        192.168.XX.X#53

Name:   localhost
Address: 127.0.0.1

[root (at mark) derelik web]# nslookup 127.0.0.1
Server:         192.168.XX.X
Address:        192.168.XX.X#53

1.0.0.127.in-addr.arpa  name = localhost.

If you get different results or if it doesn't resolve, then your DNS server 
doesn't have the records for localhost, which it should have.

-- 
With best regards,

Michael Stauber