DNS blocklist

Why is my email rejected?

If you are here as a result of a bounced email telling you to come here, it is most likely that you are (or more likely, your ISPs mail server is) listed in a block list (DNSBL).
This normally means that the IP address in use has been used to send spam, or is an easily compromisable computer that could be used to send spam.
This page will test the supplied IP address against the blocklists that we use and direct you to the appropriate site to find out why you are blocked and how to get de-listed.

Our mail server is configured not to 'drop' email - it will either get rejected, delivered locally, or accepted for forwarding to another mail server. If we accept a message for forwarding but the upstream mail server rejects it, we will send a bounce message back (as per the rules).
There are various reject codes (SMTP status 5xx codes) that we use, including 553 for a source listed in a dns blocklist, and 554 for messages containing a virus. The error code is always followed by some descriptive text explaining why we rejected the message, which will normally be passed back to the sender by means of a bounce message, which is probably why you came here.

huh? what does that mean?

If you don't know what an IP address is, you want more information on e-mail transport or are confused by the above text, please consult a computer technician or your company's IT department.

What blocklists do you use?

The blocklists we use are prone to change from time to time, but currently we use spamhaus.org (sbl + xbl) and a private list maintained internally.
It is worth noting that spamhaus xbl itself is a composite blocklist meaning that we effectively query spamhaus SBL, CBL and OPM
For some functions, we also use a list of TOR exit nodes which are unfortunately used to mask the source of abuse.

Your IP addresses

Your current address: (ec2-18-206-12-157.compute-1.amazonaws.com)
   · Not listed
Supplied address: (ec2-34-229-62-255.compute-1.amazonaws.com)
   · listed in spamhaus as - see spamhaus.org for more information.


One or more of the relevant IP addresses was found in a blocklist. You should consult the blocklist maintainers websites for details of how to get de-listed.

What should I do now

If you have an urgent email to send through our server, please contact us for assistance - +44 (0)1728 861777.

The first thing you need to do is determine why you are listed. If you are using a dial-up internet connection, you probably have a dynamic IP address which means that if you disconnect from the internet then reconnect, you will probably be OK to continue.
The DNS blocklists will be able to show why you are listed - normally either as an open proxy, a spam source, a virus infection or some other exploit. Once you have found the problem and fixed it, you can ask to be re-tested which, when clear, will de-list you within 2 hours.
If you can't de-list yourself for whatever reason, fix the problem anyway and you should be cleared within 7-31 days, depending how many times your address has been listed.