SERVERWIDE Policy on mail for non-existent users

[TobiasP]

Hi,
is there a way to disable the "Bounce with message" option for the customer?
This option is too dangerous because my server was sending a lot of backscatter until I looked in each subscription and found one with the mail policy not set to reject.

Here is an example of a backscatter mail:

Jul 26 23:16:59 44253 postfix/smtpd[21480]: connect from unknown[186.34.52.121]
Jul 26 23:17:05 44253 postfix/smtpd[21480]: warning: 121.52.34.186.b.barracudacentral.org: RBL lookup error: Host or domain name not found. Name service error for name=121.52.34.186.b.barracudacentral.org type=A: Host not found, try again
Jul 26 23:17:05 44253 postfix/smtpd[21480]: 469339B6146D: client=unknown[186.34.52.121]
Jul 26 23:17:05 44253 postfix/cleanup[21539]: 469339B6146D: message-id=<5380468857.46017353522107611872.JavaMail.root@transito-PC.cpe.telmex.com.cl>
Jul 26 23:17:06 44253 /usr/lib/plesk-9.0/psa-pc-remote[4440]: handlers_stderr: SKIP
Jul 26 23:17:06 44253 /usr/lib/plesk-9.0/psa-pc-remote[4440]: SKIP during call 'limit-out' handler
Jul 26 23:17:06 44253 /usr/lib/plesk-9.0/psa-pc-remote[4440]: handlers_stderr: SKIP
Jul 26 23:17:06 44253 /usr/lib/plesk-9.0/psa-pc-remote[4440]: SKIP during call 'check-quota' handler
Jul 26 23:17:06 44253 spf filter[21543]: Starting spf filter...
Jul 26 23:17:07 44253 spf filter[21543]: SPF result: neutral
Jul 26 23:17:07 44253 spf filter[21543]: SPF status: PASS
Jul 26 23:17:07 44253 /usr/lib/plesk-9.0/psa-pc-remote[4440]: handlers_stderr: PASS
Jul 26 23:17:07 44253 /usr/lib/plesk-9.0/psa-pc-remote[4440]: PASS during call 'spf' handler
Jul 26 23:17:07 44253 postfix/qmgr[568]: 469339B6146D: from=<gabyf@davidsalowe.net>, size=10449, nrcpt=1 (queue active)
Jul 26 23:17:07 44253 postfix/local[21544]: 469339B6146D: to=<_plesk_bounce_*DOMAIN*@localhost.localdomain>, orig_to=<gaby@*DOMAIN*>, relay=local, delay=7.5, delays=7.4/0.01/0/0.07, dsn=5.2.1, status=bounced (Diese Adresse existiert nicht unter *DOMAIN*. Bitte Fragen Sie den Sysadmin ueber die Homepage. )
Jul 26 23:17:07 44253 postfix/cleanup[21539]: 5A83D9B6151B: message-id=<20140726211707.5A83D9B6151B@argon.bitconnect.at>
Jul 26 23:17:07 44253 postfix/qmgr[568]: 5A83D9B6151B: from=<>, size=12770, nrcpt=1 (queue active)
Jul 26 23:17:07 44253 postfix/bounce[21547]: 469339B6146D: sender non-delivery notification: 5A83D9B6151B
Jul 26 23:17:07 44253 postfix/qmgr[568]: 469339B6146D: removed
Jul 26 23:17:07 44253 postfix/smtpd[21480]: disconnect from unknown[186.34.52.121]
Jul 26 23:17:09 44253 postfix/smtp[21549]: 5A83D9B6151B: to=<gabyf@davidsalowe.net>, relay=mx.davidsalowe.net[65.254.254.52]:25, delay=1.9, delays=0/0.01/1.8/0.08, dsn=5.0.0, status=bounced (host mx.davidsalowe.net[65.254.254.52] said: 550 <> Sender rejected. (in reply to MAIL FROM command))
Jul 26 23:17:09 44253 postfix/qmgr[568]: 5A83D9B6151B: removed

is this "_plesk_bounce_*DOMAIN*@localhost.localdomain" normal?

best regards