Are your emails getting bounced? Maybe you're on a blacklist.

These days, there are countless different reasons why your email might not be reaching its destination. However, if you're getting a "bounce message" back - there's a strong chance your outgoing server's IP has been included in one or more blacklists.

Various antispam software programs use blacklists to help sort out good email from bad email. As with any system, there is room for error. Your server can be blacklisted for almost any reason, but the most common cause is that someone on your network is in reality sending spam. This doesn't necessarily mean there's a spammer in your company; it could be a system that's been exploited by spammers remotely.

Once you've figured out that you've been blacklisted, understanding and eliminating the root cause is crucial. You might get yourself off the blacklist, but if systems on your network continue to send spam - you'll quickly be listed again.

The first step is to examine the bounce message. One common cause of a bounce is simply having mistyped the recipient's email address. Another common non-blacklist cause is the recipient's inbox may have reached its capacity limit. Either of these cases should be clearly explained in the bounce email.

Example bounce message:

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. 

550-Message rejected because 202.121.209.12
550-is blacklisted at weblockspammers.net

The exact message text is a function of what software the receiving server is running. In some cases the server won't specify which blacklist you're listed on. Either way, you should use a tool to find out which blacklists you're on. If you really have a problem with a "rogue" computer on your network, you may find yourself listed on several different lists.

SpamButcher recently launched a service that monitors blacklists called BlackList Patrol. For a small monthly fee, up to three different email servers can be monitored daily to see if they've been included on any lists. By being quickly notified about the problem, you can take action and limit the financial impact of missing email.

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