If you're running an online business, you know that your list is your most important asset. And regardless of whether you're just starting out or not, if you lose a chunk of your subscribers because even just one of your emails gets flagged as spam, it's going to hurt your business.

It's vital to the ongoing success of your online business to make sure you know the difference between spam and opt-in email. Here are some tips on how to make sure you're only sending email to people who have specifically asked for it.

1. Only Use Permission-Based Email Marketing

Simply put, opt-in email (also called 'permission-based') is email sent to people who have given you permission to contact them via email. So if someone hasn't directly requested information from you, they should not be on your opt-in list.

2. Single or Double Opt-in?

Depending on the email list service you're using in your business, you may have a choice between single or double opt-in email. With single opt-in, someone gives you their email address once and they are added to your list. With double opt-in (also know as confirmation opt-in), someone gives you their email address, to which they then receive an automated response from your list service asking them to click a specific URL to confirm that they do in fact want to be added to your list. Only once they click that link are they then added to your list.

So, which should you use? It depends, but for your main email list, I want to encourage you to use the double opt-in process. It means that you will lose a certain percentage of those people who signed up for your list because they then don't confirm their subscription, but it protects you from being labeled as a spammer.

3. Post Your Privacy Policy

Wherever you give people the option to sign up for your list, make certain your privacy policy is clearly stated. Something like "We will never share your email address, period" should be fine.

4. Avoid Content Filter Triggers

In your subject line and message body, avoid common words that make your message look like spam. For example, don't use words or phrases like FREE, guarantee, or increase income. Avoid using excessive punctuation or symbols, and phrases like "click here" as well.

5. Have a Clear Unsubscribe Link

In every email you send to your list, have a clear way for your reader to unsubscribe if they desire. Usually this is in the form of an unsubscribe URL at the bottom of the email. When someone clicks on the link, they should be taken to a page where they can remove their email address from your list. Just make sure your unsubscribe function works!

6. Get Whitelisted

Each ISP has their own rules that they use to determine if an email is spam or not. Do some research and start the process of getting whitelisted with the major ISPs, like AOL, Yahoo, HotMail/MSN, etc. Doing so is worth the time and effort required to protect your email from being considered spam.

At the very least, implement these 6 strategies in your online business today if you're not already. Then check with your email list service provider about other ways to protect your email from being flagged as spam. Protecting your list like this acts as an insurance policy on your bottom line. You may not like making the 'payments' on that insurance but you won't be sorry that you put it in place.