DNS Blacklist Database
In order to combat SPAM, many ISPs and mail service providers are using DNS Blacklists or Email blacklists to block email. Occassionally, when sending out email you may find that your email has been blocked. You will notice that while sending email, you receive a message that says "The message could not be sent because one or more of the recipients was rejected by the server. .....The IP address of the sender was found to be in a DNS blacklist and therefore refused."
We have not seen the issue in relation to web hosting or email hosting customers but in one case related to the ISP of a web hosting client. The information below was collected in assisting this customer and may be beneficial to others.
How do you check whether it is your ISP or your mail server that is being blocked?
You need to take the ip address that is in the error message. An ip address is a set of numbers separated by dots. Then go to http://www.dnsbl.info/dnsbl-database-check.php to check the IP address of your computer (sender's ip address) and IP address of your mail server. When clicking on this link, your computer's ip address will be automatically populated and tested, so you need to enter your mail server's ip address manually, and make sure that the site doesn't simply retest your computer's ip address accidentally.
This DNS blacklist check will indicate whether or not you are listed on any of the current DNS blacklist databases.
You then need to click on the individual databases and check the instructions for having your ip address delisted.
Should I pay to have my ip address delisted?
Some DNS blacklists will ask for payment to be delisted quickly. It is not a good idea to pay to be delisted because there are many databases, and deleting your ip address from one database does not remove you from others or diminish the likelihood that your ip address will be added to the DNS blacklist again. You need to work with either your ISP or mail hosting provider to resolve this issue.
You may very well be sharing an ip address with a someone that SPAMs and as a result, their actions will continually add the ip address to the DNS blacklist databases and affect your ability to send mail and because various ISPs use different blacklists, you may find that it affects some recipients' email addresses and not others.
What to do if you are a client of Passion Computing and believe that you are on a DNS blacklist database?
After you have used the domain above to check your IP addresses, if you find an offending ip address to know who the Netblock owner is, use
http://www.apnic.net - Asia Pacific NIC
http://www.ripe.net - Europe NIC
http://www.arin.net - American NIC
to determine the owner of the ip address. This will tell you if it is your hosting provider or your ISP.
If it is your ISP, you need to contact them to resolve the issue, if you believe that it is related to your mail service, please send to sales@passioncomputing.com.au , the error message and any information relating to the problem.
How will the issue be resolved?
It may not be easy to resolve the issue, as some ISPs are web hosting providers are slow to respond and may not want to clean up their network from spammers. Spammers may be other customers or simply using weaknesses in the network to send email. Also, the affected ISP or web host will have to write to the individual DNS blacklists to be delisted, and depending on the ISP or web hosting company, it may take weeks to resolve, if ever.
If all else fails?
If you find that you can't get a happy resolution with your ISP, you will need to change Internet Service Providers or pay for a static ip address, so that you no longer share an ip address with other users. Of course, this ip address will hopefully not be blacklisted but if it is, you can work through the DNS blacklists to get it removed.
If your web host's mail server is being listed in DNS blacklists, and they are unwilling to resolve the issue, you can change web hosting or mail providers.
Email hosting plans - affordable email hosting plans with domain forwarding and professinal support.
Webhosting plans - affordable web hosting plans with professional support
Changing web hosting providers is not difficult if you host a HTML website and more difficult if it is a database website but you may find it easier to simply register another domain name and add email hosting to this domain name.