CYBERCity RBL (Realtime Blackhole List) Usage

What Is A Realtime Blackhole List or RBL?
CYBERCity utilizes several Realtime Blackhole Lists (RBLs) to block the proliferation of SPAM.  In practice, RBLs effectively block more than 95% of the SPAM that hits our server and is an invaluable tool for providing clean inboxes for our clients.  On average, 100,000 spam messages per month are blocked.  RBLs are not perfect though, and occasionally a legitimate email is blocked.

I'm Getting An Error: 501 5.7.1 Sender Refused
If you are visiting this page and cannot send mail to our server please Contact Us and be sure to include the To: and From: email addresses.  If you are sending to a recipient on our server we can whitelist your domain name so you will have no future trouble sending mail.

I'm Getting An Error: Sender refused by the DNSBL rbl.domain.org - Sender IP=xxx.xxx.xxx.xxx
This is the same error as above.  Note your IP address shown in the error message.  You can use the lookup tool at www.rbls.org to see what RBL lists you are listed on.  Contact Us and be sure to include the To: and From: email address of your email so we can whitelist you.  You MUST include the To: and From: address so we can verify you are trying to email someone on our mail server.  After you are on the whitelist you will be able to send your message through.

What RBLs Does CYBERCity Use?
Below is a list of the RBLs we implement and links to detailed information pages.

RBL		Website		Details
xbl.spamhaus.org		www.spamhaus.org/xbl/		The Spamhaus Exploits Block List (XBL) is a realtime database of IP addresses of illegal 3rd party exploits, including open proxies (HTTP, socks, AnalogX, wingate, etc), worms/viruses with built-in spam engines, and other types of trojan-horse exploits.
sbl.spamhaus.org		www.spamhaus.org/sbl/		The SBL is a realtime database of IP addresses of verified spam sources (including spammers, spam gangs and spam support services), maintained by the Spamhaus Project team and supplied as a free service to help email administrators better manage incoming email streams.
bl.spamcop.net		www.spamcop.net		The SpamCop Blocking List (SCBL) lists IP addresses which have transmitted reported email to SpamCop users. SpamCop, service providers and individual users then use the SCBL to block and filter unwanted email.  The SCBL is a fast and automatic list of sites sending reported mail, fueled by a number of sources, including automated reports and SpamCop user submissions.  The SCBL is time-based, resulting in quick and automatic delisting of these sites when reports stop.
relays.ordb.org		www.ordb.org		ORDB.org is a non-profit organisation which stores a IP-addresses of verified open SMTP relays.  These relays are, or are likely to be, used as conduits for sending unsolicited bulk email, also known as spam.
cbl.abuseat.org		cbl.abuseat.org		The CBL takes its source data from very large spamtraps, and only lists IPs exhibiting characteristics which are specific to open proxies of various sorts (HTTP, socks, AnalogX, wingate etc) which have been abused to send spam, worms/viruses that do their own direct mail transmission, or some types of trojan-horse or "stealth" spamware, without doing open proxy tests of any kind.
spam.dnsbl.sorbs.net		www.dnsbl.nl.sorbs.net		List of hosts that have been noted as sending spam/UCE/UBE to the admins of SORBS.  This zone also contains netblocks of spam supporting service providers, including those who provide websites, DNS or drop boxes for a spammer.  Spam supporters are added on a 'third strike and you are out' basis, where the third spam will cause the supporter to be added to the list.
bl.csma.biz		bl.csma.biz		As a public service, McFadden Associates maintains free DNSBL SPAM blacklists.  Any servers sending SPAM through their mail filters will be automatically added for a period of thirty days or until removal is easily requested via their website.

We regularly evaluate and test other RBLs for effectiveness as they become available.  Most users will find RBL blocking of spam to be a time-saver and unobtrusive.  We regularly evaluate and test other RBLs for effectiveness as they become available.  If you have any other questions not answered above please Contact Us.