Testing for email open relays


Note: The names and addresses have been changed to protect the innocent.

telnet mailserver.foobar.com 25
Trying 10.0.0.1...
Connected to mailserver.foobar.com.
Escape character is '^]'.
220 mailserver.foobar.com ESMTP Sendmail 8.11.2/8.11.2; Sat, 31 Mar 2001 13:07:14 -0500 (EST)
ehlo evil.com             <-- Note: The HELO/EHLO is not required for many mailservers
250-mailserver.foobar.com Hello badguy.somewhere.com [10.2.1.1], pleased to meet you  <-- Note, the REAL name and
250-ENHANCEDSTATUSCODES                                                                                                                          IP are in the Hello reply
250-8BITMIME
250-SIZE
250-DSN
250-ONEX
250-ETRN
250-XUSR
250-AUTH LOGIN  DIGEST-MD5 CRAM-MD5
250 HELP
mail from: blaw@something-made-up.com
250 2.1.0 blaw@something-made-up.com... Sender ok
rcpt to: blaw@somewhere-else.com
550 5.7.1 blaw@somewhere-else.com... Relaying denied   <-- This shows that the mailserver is not an open relay
quit
221 2.0.0 mailserver.foobar.com closing connection
Connection closed by foreign host.
 


Copyright © 1993-2001 by Robert Barnes

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