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Email Blacklists

What is a blacklist and how does it work?

Everyone with a mail server has the right to restrict what can and can't pass through to their network. People trying to send email to a particular server are essentially a "guest" on that network. If those guest privileges are abused, the network administrator has the ability and the right to then block the abuser from sending anything to their server. To manage these blocks administrators use a blacklist that specifies who is not allowed to send email to their server.

Many email administrators use their own blacklists, but there are also blacklisting services that are available and used by many email services. An admin can then "subscribe" to a blacklist service and anything that ends up on that particular blacklist will then be blocked from sending email to them. They may also choose to filter the email as spam rather than blocking it altogether.

These blacklists either help reduce the amount of spam being received at a mail server or to filter spam to junk mail or quarantine folders. Every blacklist used is different, although providers that constantly allow spam to be passed through their servers unchecked can expect to find themselves on many different blacklists.

What if my domain is blacklisted?

Blacklists usually aren't based on a domain name. So if your email address is mail@xyz.com, it is unlikely that the xyz.com itself will end up on a blacklist. Instead, the IP address (or addresses) that are used to send email is what would end up on a blacklist. So even though your email may be fine, and no spam or viruses have been sent out from your email, someone else using the same email servers to send a lot of spam, but using abc.com, may cause everyone else to be blacklisted.

It is also common that the person or domain that the spam is coming from is unaware that they have done so. Computers that get infected with viruses or other malware can be used to send out spam. People also responding to "phishing emails" from scammers trying to get you to hand over your username and password information can also have their email accounts used to send spam. Or simply having a poor password that is easily guessed, such as 123456 or password, can allow a spammer access to the mailbox to send out spam. Any of these can result in a mail server being blacklisted.

How do I find out if I am blacklisted?

You may get a bounce back message that tells you the email couldn't go through because it was blocked or blacklisted. If the email is ending up in a junk mail or quarantine folder because of a blacklist, it will usually say in the email headers that it was blacklisted. You can often check some of the more common blacklisting services by putting in the IP address the email is sent from and see if it is blacklisted. There are websites (such as http://www.mxtoolbox.com/blacklists.aspx) that will check several blacklists at once as well.

How do I get removed from a blacklist?

Contact your email provider. Usually the email provider will need to stop whatever activity is causing them to be blacklisted before getting themselves removed from the blacklists. If the malicious activity isn't stopped first, and they get removed from the blacklist only to end up back on there, it becomes a lot more difficult to get removed the second time.

Many of the blacklist services have links on their websites to get removed from their blacklist. However, again, if the reason for the initial blacklisting isn’t addressed first, you are likely to end up back on there again and will have a more difficult time getting off the list again.
 

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