Has Your Exchange Server Been Blacklisted?

Blacklisted
If your Exchange server has been blacklisted, then you may already be aware of the trouble you face and the complexities involved in fixing this problem.  Regardless of the quality of your email, from time to time anyone could end up on a blacklist.  Being on a blacklist can be a painful experience because it can cause your email to be blocked, deleted, or put in the spam folder.  The end result is that your intended recipients may not receive your email, disrupting your ability to communicate with them.

At SocketLabs we have come to learn a lot about blacklists so I wanted to offer a simple primer on blacklists along with some advice.  I will also explain how our On-Demand service can be used as a smart host to get your mail stream flowing again right now, and how we can help you managing the outbound mail stream from your Exchange Server going forward.

What Email Blacklists Are

Email Blacklists were designed to block unwanted Internet email.  There are different types of blacklists, such as URL/domain or IP based blacklists.  This article is going to focus on IP based blacklists, since this is the type of blacklist that normally would affect your Exchange Server as a whole.  IP based blacklists contain lists of IP addresses that the blacklist operator believes to have been linked with spam in the past, or for some other reason should be suspect.  If the IP address of your Exchange Server ends up on an IP based blacklist, it could affect the delivery of all the mail being sent by your server.

Blacklists are created and maintained by third parties (operators) and they are not all equal.  In order for a blacklist to be effective, it must be referenced.  In other words, just about anyone can start a blacklist, but if ISPs or mail clients don’t refer to that blacklist when making decisions on the delivery of your mail, then that blacklist may not be as important to you.  Most ISPs and mail clients only check a limited number of blacklists for various reasons such as policy and performance.  If you found out that you are on a blacklist because people are not receiving your blacklisted email, then that particular blacklist is probably important to you.

Why You Might Have Been Put on a Blacklist

Determining exactly why you were put on a blacklist can be difficult as the blacklist operators do not want to divulge too much of their detection systems, to keep spammers from reverse engineering (and thereby avoiding) their detection.

Some of the more common ways to end up on a blacklist are:

  • Sending email that causes a lot of complaints.  Too many recipients complaining about your email can easily land your IP on a blacklist.
  • Sending email that contains viruses or malware.
  • Sending email to a spam trap email address.  A spam trap address is an email address specifically used to catch senders with bad lists.  A spam trap address could be a very old and no longer used email address, or one that has been set up and posted to a web page to catch people scraping email addresses.

Even if you are confident that your outbound email is very clean, it may be that a computer on your network has been compromised and a virus on that computer is sending spam or other malware through your Exchange Server.  This is not uncommon.

How to Check If You Are on a Blacklist, and What to Do about It If You Are

If you are reading this article, there is a good chance you already know that you are on a blacklist.  If you are on one blacklist, however, you may likely be on others as well.  A good tool for checking blacklists is Debouncer (www.debouncer.com), which currently claims to check 123 blacklists.  Debouncer can automatically check for blacklistings on a regular basis and notify you via email if it finds your IP or domain on a blacklist.  Debouncer is one of the many tools and resources our email delivery experts utilize to help ensure that email delivered through SocketLabs On-Demand is not affected by blacklistings.

If you are on a blacklist, the first thing you need do is to try to figure out why you were put on the blacklist and correct the issue.  For example, correcting the issue may involve cleaning your email lists or running virus scans on your computers to detect and remove any malware sending spam through your network.

Getting Off of a Blacklist

Blacklists are run by different operators on the Internet, so the procedure for getting off of a blacklist (which is usually possible, though not always) depends on the specific blacklist you are on.  Most blacklist operators have an online form that you can complete to request removal.  Before requesting removal, you should first ensure that you have corrected the problem that landed you on the blacklist in the first place.  Blacklist operators are concerned about the integrity of your email, and if you repeatedly ask to be removed for the same problem they may eventually reject your request.

How SocketLabs Can Help Right Now — and Going Forward

Many people that use Exchange Server also use our SocketLabs On-Demand service as a “smart host” for their Exchange Server.  When you use SocketLabs On-Demand service as a smart host for your Exchange Server, it causes your Exchange Server to pipe all of its outbound email through our cloud based email delivery network over our IP address space.  Our advanced delivery network and proprietary technologies help to prevent blacklistings, and our email delivery experts help to avoid blacklists by keeping our network spam free.  We do not tolerate spam on our network.

Setting up SocketLabs On-Demand as a smart host is fast and easy and can usually get the email from your Exchange Server flowing again right away. It is critical that you clean up the source of your problem before sending your email through our service, however, otherwise you will simply have the same problem again.

If you are unfamiliar with setting up a smart host in Exchange, the procedure varies with different versions, so the best place to find help may be from Microsoft or by searching online.

To sign up for a SocketLabs On-Demand account, click here.  All of our plans (including free) can be used as a smart host.

Here are some other related articles that may be helpful:

How Can A Smart Host Improve Deliverability For Your Business?
When Using a Smart Host is the Smart Choice