Prevent SMTP Open Relay 1


I want to write howto fight back smtp open relay from mail administrator view ...
I used qmail for my mail server so ...

Qmail is VERY secure and, by default, it does NOT allow open relaying. As a matter of fact, you would have to make some intentional and deliberate modifications to Qmail in order to get it to be an open relay. Now the next question I get is "But does the Qmailrocks.org installation allow open relaying?" Again, a simple answer. NO. Qmailrocks.org's Qmail installation, while containing a lot of bells and whistles, is still at it's core Qmail. The Qmailrocks.org Qmail installation does not deviate from or tamper with Qmail's inherent instructions that open relaying is BAD and should never be allowed by default. In the end, the answer to these questions and other similar questions comes down to a questioning of Dan Bernstein himself. Raise your hand if you think Dan Bernstein would be idiotic enough to allow open relaying in Qmail by default. No hands? That's what I thought. Dan's no dummy, folks.

Because default configuration on qmail relay conf ( /etc/tcp.smtp ) like this ...

127.:allow,RELAYCLIENT=""

But if you want to accept relay for another network ( ex: 192.168.0.0/16 ) , just edit your /etc/tcp.smtp like below ...

127.:allow,RELAYCLIENT=""
192.168.:allow,RELAYCLIENT=""

Maybe some smtp open relay, their /etc/tcp.smtp configuration like this ....

.:allow,RELAYCLIENT=""

Oooo ... crazy and dummy admin ...

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