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What is Spam Blocking and how to fix it
  • The information here is given only as a guide any changes you make to your computer and or networks is done so ENTIRELY AT YOUR OWN RISK . Calco UK do not accept any responsibility for any changes you might make to your computer or network using the information herein.















    Someone phones you and says they sent you an email but didnt get a reply from you. They try again and it still doesnt get to you. They get a MAILER-DAEMON (Mail Delivery System) message that says something like:

    This is the Postfix program at host

    I'm sorry to have to inform you that the message returned below could not be delivered to one or more destinations.

    <>: host SomebodyDomainsNamesLtd[999.16.223.41] said: Error 550 <>... Notify your ISP that their 999.171.216.71 is
    blacklisted by

    What on Earth does all this mean ?
    What are the consequences ?
    How do you fix the situation ?
    Who are the people concerned and what do the big words mean ?

    The IP addresses in the above example are fake and just examples .. as are ALL the names of companies herein. The information here is given only as a GUIDE any changes you make to your computer and or networks is done so ENTIRELY AT YOUR OWN RISK it is not advice or intended as instruction on how to repair computers. Calco UK Ltd do not accept any responsibility for damages caused by any changes you might make to your computer or network using the information herein.

    What Does this mean?
    Simply you mail is being blocked by whoever runs your email address.

    So for example if you buy an email address called from Somebody Domains Names Ltd, then THIS company is blocking the email.


    What are the Consequences?
    You will not get email for the period of the automated block. Normally 3 to 7 days. Unless some kind customer calls you, you wont know its happening and could loose business


    How to get your email working again?

    Call Somebody Domains Names Ltd and explain what is happening. They may be helpful and remove the block - or remove the email address from their spam check. Unfortunately they may be unhelpful and blame someone else for the problem.


    In the above example the following means: (your email address with the problem)
    999.16.223.41 (The ip of the company blocking your email)
    host (The company blocking your email)

    999.171.216.71 (The ip of the company blocking your email) (the spam database company)



    Now the same information in more detail...

    When someone sends unsolicited email selling something (pills, fake watches etc) or asking for money its called spam. The software that prevents this happening is called a spam blocker. Internet companies use software that does this to shield customers from Spam. Its works by consulting a list of offenders. The list is like a list of telephone numbers called IP addresses in this example:-


    If the IP address is on the list then the system blocks the email and sends back a message in technical jargon saying whats happened.

    Unfortunately over zealous spam software can block not just the offender, but also the IP addresses on either side too. Some particularly bad companies block whole ranges of IPs, preventing ANY remedy other that asking to be removed from the list. Some companies charge an "administration fee" of 50 Euro to have your mail removed from their blacklist immediately.

    If you wait 7 days, then normally your email address will be removed from the blacklist and your mail will function as normal.


    What is a false positive?
    In this instance ... This is when someone is blocked because someone else is being a nuicense or breaking the law. Example: Say the mail computer (server) in telehouse has 100 customers with all their email accounts on it. The mail computers address is 999.16.223.41 Someone else (not you) starts sending out unsolicited emails to hundreds of random strangers. The spam systems in the spamhouse data company gets wind of this behaviour and traces the culprit to the computer with IP address 999.16.223.41 ... the same mail server that you are on. They immediately block 999.16.223.41 and so from that moment on your mail is blocked. Some possibly over zealous spam data companies block not just the offending computer but all the computers nearby from 999.16.223.0 to 999.16.223.255 a total of 256 machines.


    The sad reality of this situation is that unless a kind customer takes the trouble to phone you to tell you that they got the MAILER-DAEMON (Mail Delivery System) message then you will never know about the problem and therefore unable to fix it. Result = loss of business.


    The problem is global and common. Most Internet companies use some kind of Virus and Spam software to prevent their custmers from getting too much spam. However the difference comes when you ask for help. Good companies will explain whats happening and try to help you. Other companies however tend to do nothing and blame someone else for their actions. Because there are at least 4 people involved its very easy to confuse and obfuscate i.e. blame someone else. They could be :-


    The ISP (the company running your email)

    The Broadband Provider
    The Spam Data checking company
    The Website Developer


    Lastly but not least ... Calco UK have a policy of helping our customers to the best of our ability. So if you need help just call us and we can at least advise on the best course of action or help find a solution. Tel: 0845 2579460


    Possible Solutions


    First of all... make sure you have the correct information available about your email account and explain the problem to them as clearly as you can. This may take several attempts as the problem needs a lot of jargon to explain it. If you dont understand what you are being told; ak for it to be explained again in more simple terms. Get a ticket number, the agent's name and direct line if possible.

    Change the server IP address to something other than 999.16.223.41 This is moving the email address physically from one computer to a different one and not really an option if the mail from a large (national) hosting company is being blocked.


    Trace the spam blocking database company (it should be listed in the email) and put in a request to have your IP address cleaned or taken off their blacklist. Most spam houses have a box on a webpage for this. Oddly enough some companies charge 50 Euros per IP address for instant removal.


    Wait 3 to 7 days for the spam listing to come of the blacklist. Although this seems lazy and inadequate, only the Internet Companies participating in spam shielding using the company blacklisted by will be blocking your mail. All other companies should be unaffected. Bear in mind though that people such as Fasthosts, 1&1, Heart Internet etc account for the bulk of hosted websites in the UK so it could be a serious issue if your business & clients are UK based AND if a large company such as one of the aforementioned is being blocked.


    Request your ISP (or the persons running your email address) to be taken off their spam checking procedure for a week or so till the problem fades.


    Request your ISP (or the persons running your email address) take any Spam Data company with a reputation for frequent false positives of their checking procedure(s)


    Set up a new email address with a different mail company so that the new IP address is completely different from the problem one.


    Change ISP and your email to one without this problem


    Other Mail Advice


    Have a backup email address from Google or Bing etc.
    If your regular email address gets blocked you can use this one till the problem fades in a week or so.


    Check any Mail Forms on your website once a week

    In addition to the above we reccommend that ALL users of mailforms, irrespective of ISP, Web Company orTeleco, check their circuit once a week now.

    This is a simple procedure whereby the user (you) fills out the mailform on their own website(s) giving their own details. You should then receive the form as normal within an hour (mail need not be instant as normally assumedat busy periods). If you dont you should contact us as soon as possible and we will find out why its not working.

    The reasons for this constant checking policy are many, however the problem arises whenas you correctly say from NOT KNOWING when the form is down andthe subsequent loss of business. Checking the form regularly will catch the problem early. Sadly we cannot guarantee a form will work as the scripting they rely on, is constantly updatedAUTOMATICALLY by software vendors and we are not informed when they do so.

    Forms are alsospammed by the "bad guys" causing spam so again consistant checking helps in keeping things working.

    If you think there is a problem with our email services you can always check if our service has been affected in any way by checking our service status page at

    We have a continuing commitment to quality of service and a transparent policy of informing clients when things have gone wrong and when they have been put right again.





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