Eメールの不正中継がされていないかチェックしたい

 自分が管理をしているマシン上でメールサーバが稼動している場合,スパムメールなどの踏み台にならないよう中継をチェックしておくことは必須事項だ。ある日突然にスパムメールの苦情などが届かぬよう,自らのチェックをしておきたい。

 次のようにサーバ上で「mail-abuse.org」にtelnetをすると,9項目(現在は十数個の不正なメール中継のチェックを行う)の中継処理を自動的に行ってチェックしてくれる。すぐにでもできる手軽な方法だろう。

$ telnet relay-test.mail-abuse.org
Trying 204.152.184.74...
Connected to mail-abuse.org.
Escape character is '^]'.
Connecting to 202.217.96.xxx ...
<<< 220 xxxx.xxxx.eyep.net ESMTP Postfix (Snapshot-20001121)
>>> HELO dante.mail-abuse.org
<<< 250 xxxx.xxxx.eyep.net
:Relay test: #Quote test
>>> mail from:
<<< 250 Ok
>>> rcpt to: <"nobody@mail-abuse.org">
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 1
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 2
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #test 3
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 4
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 5
>>> mail from: <>
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 6
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 7
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address rejected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 8
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 554 : Recipient address re
<<< 554 : Recipient address re
jected: Relay access denied
>>> rset
<<< 250 Ok
:Relay test: #Test 9
>>> mail from:
<<< 250 Ok
>>> rcpt to:
<<< 250 Ok
>>> QUIT
<<< 221 Bye