Server Fault Stack Exchange
Server Fault Stack Exchange

Questions tagged [rbl]

Real-time Blackhole is a database of IP addresses known to send spam, accessible over DNS, with specific responses to determine whether a host should be rejected or allowed.

A Domain Name System-based Blackhole List (DNSBL) or Real-time Blackhole List (RBL) is an effort to stop email spamming. It is a "blacklist" of locations on the Internet reputed to send email spam. The locations consist of IP addresses which are most often used to publish the addresses of computers or networks linked to spamming; most mail server software can be configured to reject or flag messages which have been sent from a site listed on one or more such lists. The term "Blackhole List" is sometimes interchanged with the term "blacklist" and "blocklist". https://en.wikipedia.org/wiki/DNSBL

61 questions
21
votes
4 answers

What are the best methods for catching snowshoe spam?

I'm using Smartermail for my small mailserver. We've been having a problem lately of getting waves of snowshoe spam that follow the same pattern. They come in batches of 3 or 4 at a time. The bodies are almost identical save for the domain name…
pooter03
  • 436
  • 3
  • 11
11
votes
5 answers

How do I remove IP from sorbs.net blacklist?

Our email server has ended up in the sorbs.net blacklist and we're going round in circles trying to get it removed, currently this is causing down-time between our suppliers. I am a developer and not familiar with Sorbs but asked if I could take a…
Brett Ryan
  • 327
  • 1
  • 4
  • 15
8
votes
3 answers

Why is my email server in AT&T's blacklist?

I just got this bounce message: <████████@att.net>: host scc-mailrelay.att.net[204.127.208.75] said: 521-88.208.246.34 blocked by sbc:blacklist.mailrelay.att.net. 521 DNSRBL: Blocked for abuse. See http://att.net/blocks (in reply to MAIL…
legoscia
  • 298
  • 1
  • 3
  • 14
7
votes
2 answers

How to enable RBL checking in postfix?

How to enable RBL filters in postfix? My current configuration: submission inet n - n - - smtpd -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes -o…
Sfisioza
  • 592
  • 2
  • 7
  • 18
6
votes
2 answers

Spamassassin: Bypass /etc/resolv.conf DNS for querying DNSBL?

Question Is there a way to let spamassassin bypass my linux system's dns servers to query DNSBLs? Background Info When my Server receives email, it is checked by spamassassin. One of this checks looks up the involved mail servers in DNS blacklists.…
geruetzel
  • 143
  • 1
  • 1
  • 12
6
votes
2 answers

Which DNS Black Lists would you recommend to discard spam in pre-queue?

There are many black lists out there, with bad and good reputations. Also, some people recommend to use RBL lists only in score-based systems (like spamassassin) while others (including commercial service providers, think Barracuda) extensively use…
Luke404
  • 5,708
  • 3
  • 44
  • 58
6
votes
1 answer

Postfix Whitelist before recipient restrictions

Alright. Some background. We have an anti-spam cluster trucking about 2-3 million emails per day, blocking somewhere in the range of 99% of spam email from our end users. The underlying SMTP server is Postfix 2.2.10. The "Frontline defense" before…
grufftech
  • 6,620
  • 4
  • 35
  • 37
5
votes
2 answers

Postfix: ACCEPT if RBL and SPF checks pass, DUNNO/greylist otherwise. How to do it?

I would like to accept all clients that pass RBL and SPF checks (and possibly some checks, but these are minimum requirements for me), and greylist those who don't. When a client passes the SPF check (SPF record exists, no fail, no soft-fail), we…
michau
  • 51
  • 6
5
votes
1 answer

How Does DNSWL work? How can I gain better trust?

How does DNSWL work? It's clear to me when someone report a spam, but how can I gain a higher score/trust? Do some companies report "good" servers? Or will the score go up with time without reporting spam to them?
mvorisek
  • 485
  • 6
  • 19
4
votes
2 answers

Best Postfix spam RBL policy weight daemon?

I just heard about policyd-weight so I did an apt-cache search policyd which returns three options: policyd-weight postfix-policyd postfwd Which one is the best, and do you have any tips on setting them up? Our current setup is whitelister plus…
TRS-80
  • 2,564
  • 17
  • 15
4
votes
1 answer

Which RBL's does sophos use?

Anyone know where I can find the a list of which RBL's Sophos use's? I have checked their website with no luck, and currently awaiting a response from their technical support. Thank You in advance Kevin
Kevin
  • 87
  • 1
  • 7
4
votes
3 answers

Customer's IP Listed on RBL - What steps do you use to prevent black listing?

Customer called saying their e-mail was bouncing from particular vendors. Investigated it and identified they were listed on more than one RBL/CBL. Restricted firewall to only allow traffic on port 25 from mail server. Then requested removals…
Lucille
  • 219
  • 2
  • 4
3
votes
0 answers

Combating a persistent spam list

We use Office 365 as our primary mail provider. We have an internal mail server that we use for relaying things like reports from our SSRS, scan to inbox for old scanners, etc. It is an IIS SMTP on server 2008R2. This server is not exposed through…
Sabre
  • 283
  • 1
  • 10
3
votes
1 answer

Configure Barracuda Spam Filter behind Postfix to use client IP when do RBL-checking

I have the following setup: Internet -> Postfix Mail setup as Proxy -> Barracuda Spam Filter -> Microsoft Exchange I have tried searching through the documentation and configuration panels to see how I could get the Barracuda to use the original…
mrkmg
  • 73
  • 7
2
votes
1 answer

DNS server in RBL

While SMTP servers should not be on RBL, to ensure deliverability of emails, what about DNS servers themselves? Does it matter? I am asking this question because multiple Route53 DNS servers are on various RBL, mainly SORBS. I understand that…
BrightMorning
  • 21
  • 2
1
2 3 4 5