Preventing backscatter with sendmail

Steve Freegard steve.freegard at
Mon Jan 26 09:08:45 GMT 2009

Gareth wrote:
> Havent been following the spamassassin tread but for postfix to stop
> creating backscatter yourself use recipient verification.
> To remove backscatter either use the mailscanner watermark feature or if
> outgoing mail doesnt allways go through mailscanner then you can use the
> spamassassin 'vbounce' plugin instead.

For Postfix you should really configure and enable the 'verify' daemon
if the machine scans messages for non-local users.  See

That will prevent *you* from causing backscatter.  Any time you accept a
message where an upstream SMTP server will do an SMTP 5xx rejection will
cause you to generate an NDR to the envelope-sender (invalid recipients
being the most common cause of this).


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