Sometimes you think you’re doing everything right – you’ve designed a fabulous emarketing campaign, segmented your audience for maximum open and click rates, included multiple calls to action, and scheduled delivery in the middle of the sweet spot (as we’ve been taught, Tuesday-Thursday, 11am-2pm). But, alas, you’ve been blacklisted.

So, why are emails blacklisted? The horribly vague answer is… it depends.

Blacklists are a collection of IPs, URLs, and email addresses flagged as spammers or phishers that may harm computers, networks, or websites. Spammer is a dirty word that you do not want associated with your company because it implies that you send unsolicited and unnecessary messages with irrelevant information.

Blacklists are designed to reduce spam. If you’ve been blacklisted, then many of your emails will not be delivered and you will notice a dramatic decrease in email open rates and an increase in bounce back messages.

First of all, there are a couple of different traps your emails can get stick in, either blacklists from public ISPs or Postini spam filters.

Public ISPs are the IP addresses that your home or business router receives from your internet service provider (ISP). Devices with these public IP addresses can communicate with other public IP address devices, but not directly with private IP addresses (this requires a router). Most major ISPs have their own internal blacklists – Outlook and Yahoo maintain theirs inside custom spam filters and do not allow you to query on their lists to check whether or not you’re blocked.

There are more than 120 blacklists from public ISPs. Make sure you have access to your server’s IP address so you can monitor public blacklists. Check the following websites to ensure your IP address hasn’t been flagged:

The good news is all email marketing starts with a clean slate. Let’s say you’ve just started using marketing automation software (cough, Salesfusion, cough, cough) and are ready to launch your first email campaign. To stop blacklists in their tracks, check that you’ve completed the following steps before clicking send:

Then there’s Postini.

Postini is an email and web security/archiving service. Owned by Google, Postini offers cloud computing services for filtering email spam, encrypting messages for security, and archiving web communications. Businesses that use Postini redirect their incoming and outgoing emails through Postini instead of their own email servers. Messages are scanned for viruses and malware and anything deemed as spam is filtered out.

The frustrating thing about Postini is that it can not only block your message, but then not explain why. Solving the mystery often comes down to lots of testing with a healthy dose of trial and error. Here are some Postini secrets revealed:

If you do find yourself on a blacklist or trapped in a Postini spam filter, isolate the problem as soon as possible. Review the email campaign that isn’t being delivered and the bullet points above. Be sure to communicate with the specific blacklist you’ve been added to and request immediate removal.

Email responsibly to maintain a flawless reputation. Maintain an open line of communication with email recipients so they do not report you as a spammer and clearly mark your opt out links just in case.