Welcome to the most active Linux Forum on the web.
Go Back > Forums > Linux Forums > Linux - Server
User Name
Linux - Server This forum is for the discussion of Linux Software used in a server related context.


  Search this Thread
Old 06-12-2019, 07:13 AM   #1
LQ Newbie
Registered: Jun 2019
Posts: 1

Rep: Reputation: Disabled
Stop our Postfix from Sending Backscatter


we have a Postfix-Mailserver set up, to send Mails from our Domains and receive Mails to our domains.

The problem is we receive mail like this:

Jun 11 05:21:32 server postfix/smtp[27122]: GA8A71A1: to=<>, orig_to=<>, relay=...:25, delay=19, delays=19/0.01/0.07/0, dsn=5.0.0, status=bounced (host ... said: 500 Syntax error, command unrecognized (in reply to MAIL FROM command))

with: from=<???>

Our server then sends a bounce mail to this forged from-address, to inform it of this error probably, but this user doesn't exist and we get then listed by Backscatterer, because we send bounces to non-existing users.

So, how can we prevent this? We could stop sending bounces altogether, but that doesn't seem like a sensible solution. Trying to verify the sender could itself lead to producing more spam. Anybody has a good solution in Postfix for that? Thanks in advance.
Old 06-12-2019, 08:04 AM   #2
Senior Member
Registered: Feb 2013
Location: Tucson, AZ, USA
Distribution: CentOS 7.6
Posts: 3,068

Rep: Reputation: 1069Reputation: 1069Reputation: 1069Reputation: 1069Reputation: 1069Reputation: 1069Reputation: 1069Reputation: 1069
You must send bounces when the condition for them occurs to be RFC compliant.
You should not send bounces when you receive a bounce, that is, when the MAIL FROM: is <> or postmaster

I can't help you with configuring postfix to do that, tho. Sorry.

I believe that'a what is talking about, and they have instructions about how to use their RBL correctly on their site. They say they are blacklisting only 87101 IP addresses, which is nothing in the big scheme of things. I'm not sure why you care if you get listed there, even.


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Postfix and backscatter circus78 Linux - Server 1 05-21-2012 05:57 AM
Preventing Backscatter with Postfix SteveJenkins Linux - Server 6 08-30-2010 05:50 AM
Postfix Backscatter Problem glyn3332 Linux - Server 1 05-07-2009 02:28 PM
Backscatter Email (Postfix) carlosinfl Linux - Server 7 04-15-2008 09:04 AM
Duration of backscatter billymayday Linux - Security 9 01-20-2007 05:47 AM > Forums > Linux Forums > Linux - Server

All times are GMT -5. The time now is 06:04 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration