Trusted Source on McAfee Servers - http://www.trustedsource.org

DNS Stuff - A large collection of DNS utilties combined into one site. http://www.dnsstuff.com

Sam Spade - Dns tools and Blacklist Lookups. http://www.samspade.org/

DNS.net - Tools to manage DNS. http://www.dns.net/dnsrd/tools.html

Demon tools - Internet Tools http://www.demon.net/toolkit/internettools/

NW Tools - Ping / Traceroute / NSlookup/ etc http://network-tools.com/

Abuse.net relay testing http://www.abuse.net/relay.html

Open Relay Database Test - http://ordb.org/submit/

Open Relay Test http://members.iinet.net.au/~remmie/relay/

Mail Server Relay Test http://www.lucidlogic.com/relay.php

Anonymous Relay Test http://www.antispam-ufrj.pads.ufrj.br/test-relay.html

Anonymous Relay Test http://www.aupads.org/test-relay.html

Test your mail server for an open relay http://www.truson.biz/services/spam_tester.php

Third Party Relay Check http://www.rbl.jp/svcheck.php

Mailserver Open Relay Check http://msv.dk/ms009.asp

SpamHelp.org SMTP Open Relay Test - http://www.spamhelp.org/shopenrelay/

Open Relay Test - http://www.lashampoo.net/unix/testrelay

Ted's Webtools - Open Relay Test http://www.mob.net/~ted/tools/relaytester.php3

mrt - http://www.monkeys.com/mrt/

Perl rlytest - http://www.unicom.com/sw/rlytest/

Perl mtaprobe.exp - http://www.cymru.com/Tools/mtaprobe.exp

Expect SMTP Open Relay Checker - http://sourceforge.net/projects/smtprc

FreeBSD testrelay - http://www.kluge.net/~felicity/random/testrelay.txt

Perl relaytest - ftp://ftp.ruhr-uni-bochum.de/local/mail/spamtools/relaytest

Perl RelayTest - http://www.digiarch.org/relaytest.html

Win SORBS - http://sorbs.sourceforge.net/- checks incoming servers for open relays and proxies

Relay Testing Envelopes - http://www.chebucto.ns.ca/~af380/envelopes.txt

Open Relay Verifying Engine Tests - http://www.aupads.org/working.html

Relay Testing Envelopes - http://www.ki.nu/software/sendmail/orbs-envelopes.shtml

Some open relay tests - http://www.reedmedia.net/misc/mail/open-relay.html