Getting off blocklist

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If your mailer has been an open relay for some time, and particularly if it has been used by spammers, it may well be on one or more blocklist.

The blocklist are a very important co-operative activity of the anti-spam community. Certain organisations or individuals maintain lists of IP addresses or address ranges and make them available in ways which enable users of the lists to reject attempted mail transfers from those addresses. Once your mailer is working properly you should check with all the lists you know and request removal if necessary.

The lists have a variety of qualifications for inclusion and arrangements for removal.

If you try to have your mailer removed from any of the lists below but they say you are still open to relaying, it may be that the blocklist testers identify vulnerabilities of which the Janet tester is not yet aware. Please report your problem to

WARNING: Some blocklist sites have a facility similar to the Janet one for testing your mailer, but if you fail any of their tests you may be added to the open relay list concerned. Check if your mailer is already there before running their tests. If it isn't, and Internet access from that system is important, you may decide that in the short term the risk from spammers is less than the risk from being blocked.

In the long term this is not a safe procedure and you should welcome any facility for identifying weaknesses. The Janet tester tracks new potential exploits as they become known.


Mending fences

If your open relay was used for spamming, it will have made you unpopular with a wide range of people throughout the Internet.

Those who use MAPS or ORBS will mostly be satisfied when you have corrected the fault and had yourself removed from the public blocklist. Others will have silently placed you on private blocklist of which you will only become aware when mail to certain places is rejected.

Others again will send you more or less polite reports, complaints and requests that you correct the problem. These are innocent parties whom you have inconvenienced, and some of them may have tried to help you; so in most cases you should acknowledge their messages. The reply need not be long or detailed, and the same one will probably do for almost all reports; inserting suitable names and addresses in the following may be enough.

You reported receiving unwanted mail relayed through the Our College mail server (

That system had indeed been wrongly configured by mistake. We have now corrected its configuration and you should have no further mail by this route.

I am sorry you were troubled. Thank you for reporting the incident to Our College.

If another network has blocklisted you, it will of course be hard for you to send them this or any other message. You may be able to write from an account with some dialup or other service provider. Failing that, Janet(UK) may be able to forward the message; contact Janet Service Desk at