I have been blocked from sending email. Why? Now what can I do?


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Email RBL Lists


An RBL list (Real-time Blackhole List ) is a list (database) of spammers server addresses. People can configure their email software to look up these lists against their incoming email. If a piece of incoming email is from a server or person on the RBL list, their email server will reject the email and the email will be blocked. It will not get through.


The better blocking services send an email back to the spammer telling them it will not get through. Other services are more like a black hole. The email just vanishes and no notification is sent.


Your server address and email domain name could be on one of these lists.


Note: This affects you only if you send email to a person who gets their email from a server who subscribes to one of these lists. You will likely still be able to email other people. These RBL services occasionally swap list details so once you are on a list with one RBL company, you might end up on several RBL lists with several services.


How did I end  up on an RBL list?


An email sent from your organization has been flagged by someone as spam and then submitted to the list. This could have been someone who took offence to a marketing campaign or simply does not want email from anyone at your domain name. If one person is blocked, normally the whole email domain is blocked. One person can block a whole organization.


The other option, someone has been using a stolen email address and pretending to be from your company or using your email address. This is called spoofing. Someone who has nothing to do with your business could have caused the block to occur. For more information, please see spoofing.



How can I fix this ?


If you received a reply email telling you that you are blocked, the email will normally list the reasons why and tell you who to contact or what website to go to, to remove the block. If you are not reported as a spam source again (Within a time frame), sometimes lists will automatically remove you from the block after 48 hours.


Sample email reply:



Sent <<< RCPT TO:<email address>
Received >>> 554 service unavailable; client host [ServerIPaddress]
blocked using bl.spamcop.net; blocked - see

Unable to deliver message to <email address>.



Spamcop is one of many RBL lists including (not limited to):

Information from Spamcop:


The SCBL is a list of IP addresses which have transmitted reported email to SpamCop users, which in turn is used to block and filter unwanted email. The SCBL is a fast and automatic list of sites sending reported mail, with a number of report sources, including automated reports and SpamCop user submissions. The SCBL also quickly and automatically delists these sites when reports stop.

The SCBL aims to block spam with minimal blocking or misidentification of wanted email. Given the power of the SCBL, SpamCop encourages users to also actively maintain a whitelist of wanted senders of email. SpamCop also encourages SCBL users to tag and divert email, rather than block it outright. In the end, most SCBL users find that the amount of unwanted email successfully filtered makes the risks and additional efforts worthwhile.

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.


Recently a number of people I know have been using spamhaus



It has numerous lists and types of lists that it uses

SBL - Spamhaus Block List
The SBL is a realtime database of IP addresses of verified spam sources and spam operations (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.
PBL - Policy Block List
The Spamhaus PBL is a DNSBL database of end-user IP address ranges which should not be delivering unauthenticated SMTP email to any Internet mail server except those provided for specifically by an ISP for that customer's use. The PBL helps networks enforce their Acceptable Use Policy for dynamic and non-MTA customer IP ranges.

XBL - Exploits Block List
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.
For information on CBL see http://cbl.abuseat.org/
For information on NJABL see http://www.njabl.org/




There are other ways that you can be blocked

If your internet provider detects that you are sending out lots of spam (It might be a virus or some other Malware) they can tell your internet connection to no longer allow you to send email. They will then normally send you an email (you can receive) or phone you.

It is a good practice to do an online scan and then scan for Spyware and make sure you are using a firewall. You might need to scan all your computers if you are at a work email address.

Spam detection


Another way to combat spam is to run spam rules against incoming emails at the destination server. There is no central list, it would be specific to the site you have emailed.


The rules might be

  • how many times s specific word is used

  • type of attachments included in the email

  • embedded images or type of images

  • fancy fonts in the email

or you might be checked against a user and recipient list they have on their server. (These kinds of things need someone to authorize you to send the server email or you need to send a follow-up email to verify that you are human and not a robotic software spam tool.)


If this kind of block occurs, you need to contact the person you emailed to release you so that you can email them.


Note: If you have a high spam rating (determined by the rules) you and everyone who emails from your server might appear in the Outlook 2003 Junk email folder. You will need to be careful you do not end up permanently sending email classed as spam.





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To keep up to date you can refer to my blog


If you are viewing this page then these specific other pages in this series might be of interest to you:

  • Tools to remove Malware and Viruses
  • Tools to remove Malware etc but still under review by me
  • A page dedicated to helping you get the information needed to remove Malware
  • Spybot installation steps
  • How to perform an online Housecall Virus scan
  • What is Malware ?
  • Why are people using my email address?
  • How did someone steal my Email address?
  • Why is my email being blocked ?
  • How can I reduce spam ?
  • Why did I get infected ?
  • How to Handle Spam!
  • Why do I get all these bounce backs to my email address ?
  • What is a Drive-By Malware attack ?








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