This is a sample output of what you should see when you telnet to "relay-test.mail-abuse.org" from your mail server.   If any of the tests do not pass, you still have an open relay that is vunerable to spam relaying.
 

Script started on Mon Nov  5 17:23:16 2001

<yourmailserver.yourdomain.com>:[2] telnet relay-test.mail-abuse.org
Trying 204.152.187.123...
Connected to cygnus.mail-abuse.org.
Escape character is '^]'.
Connecting to 206.63.32.249 ...
<<< 220 yourmailserver.yourdomain.com ESMTP Sendmail 8.8.8/8.8.8; Mon, 5 Nov 2001 17:23:50 -0800 (PST)
>>> HELO cygnus.mail-abuse.org
<<< 250 yourmailserver.yourdomain.com Hello cygnus.mail-abuse.org [204.152.187.123], pleased to meet you
:Relay test: #Quote test
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <"nobody@mail-abuse.org">
<<< 550 <"nobody@mail-abuse.org">... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 1
>>> mail from: <nobody@mail-abuse.org>
<<< 250 <nobody@mail-abuse.org>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org>
<<< 550 <nobody@mail-abuse.org>... we do not relay nobody@mail-abuse.org
>>> rset
<<< 250 Reset state
:Relay test: #Test 2
>>> mail from: <spamtest@maps1.pa.vix.com>
<<< 551 unresolvable host name maps1.pa.vix.com, see RFC 1123, sections 5.2.2 and 5.2.18.
>>> rset
<<< 250 Reset state
:Relay test: #test 3
>>> mail from: <spamtest@localhost>
<<< 250 <spamtest@localhost>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org>
<<< 550 <nobody@mail-abuse.org>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 4
>>> mail from: <spamtest>
<<< 250 <spamtest>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org>
<<< 550 <nobody@mail-abuse.org>... we do not relay spamtest
>>> rset
<<< 250 Reset state
:Relay test: #Test 5
>>> mail from: <>
<<< 250 <>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org>
<<< 550 <nobody@mail-abuse.org>... we do not relay 
>>> rset
<<< 250 Reset state
:Relay test: #Test 6
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org>
<<< 550 <nobody@mail-abuse.org>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 7
>>> mail from: <spamtest@[206.63.32.249]>
<<< 250 <spamtest@[206.63.32.249]>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org>
<<< 550 <nobody@mail-abuse.org>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 8
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <nobody%mail-abuse.org@yourmailserver.yourdomain.com>
<<< 550 <nobody%mail-abuse.org@yourmailserver.yourdomain.com>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 9
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <nobody%mail-abuse.org@[206.63.32.249]>
<<< 550 <nobody%mail-abuse.org@[206.63.32.249]>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 10
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <"nobody@mail-abuse.org">
<<< 550 <"nobody@mail-abuse.org">... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 11
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <"nobody%mail-abuse.org">
<<< 550 <"nobody%mail-abuse.org">... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 12
>>> mail from: <spamtest@[206.63.32.249]>
<<< 250 <spamtest@[206.63.32.249]>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org@yourmailserver.yourdomain.com">
<<< 553 <nobody@mail-abuse.org@yourmailserver.yourdomain.com">... Unbalanced '"'
>>> rset
<<< 250 Reset state
:Relay test: #Test 13
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <"nobody@mail-abuse.org"@[206.63.32.249]>
<<< 550 <"nobody@mail-abuse.org"@[206.63.32.249]>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 14
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org@[206.63.32.249]>
<<< 550 <nobody@mail-abuse.org@[206.63.32.249]>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 15
>>> mail from: <spamtest@[206.63.32.249]>
<<< 250 <spamtest@[206.63.32.249]>... Sender ok
>>> rcpt to: <@yourmailserver.yourdomain.com:nobody@mail-abuse.org>
<<< 550 <@yourmailserver.yourdomain.com:nobody@mail-abuse.org>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 16
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <@[206.63.32.249]:nobody@mail-abuse.org>
<<< 550 <@[206.63.32.249]:nobody@mail-abuse.org>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #Test 17
>>> mail from: <spamtest@[206.63.32.249]>
<<< 250 <spamtest@[206.63.32.249]>... Sender ok
>>> rcpt to: <mail-abuse.org!nobody>
<<< 550 <mail-abuse.org!nobody>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #test 18
>>> mail from: <spamtest@yourmailserver.yourdomain.com>
<<< 250 <spamtest@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <mail-abuse.org!nobody@[206.63.32.249]>
<<< 550 <mail-abuse.org!nobody@[206.63.32.249]>... we do not relay spamtest@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
:Relay test: #test 19
>>> mail from: <postmaster@yourmailserver.yourdomain.com>
<<< 250 <postmaster@yourmailserver.yourdomain.com>... Sender ok
>>> rcpt to: <nobody@mail-abuse.org>
<<< 550 <nobody@mail-abuse.org>... we do not relay postmaster@yourmailserver.yourdomain.com
>>> rset
<<< 250 Reset state
>>> QUIT
<<< 221 yourmailserver.yourdomain.com closing connection
Tested host banner: 220 yourmailserver.yourdomain.com ESMTP Sendmail 8.8.8/8.8.8; Mon, 5 Nov 2001 17:23:50 -0800 (PST)
System appeared to reject relay attempts
Connection closed by foreign host.

<yourmailserver.yourdomain.com>:[3] exit

script done on Mon Nov  5 17:24:09 2001