By Jeff Kline


How To Avoid The Spam Folder

Tuesday, November 19, 2013

Spam image courtesy of

There are malicious spammers out there—those who send out emails with subject lines like “How I made $100,000 a year working at home!” and “LOSE 10 POUNDS A WEEK GUARANTEED!!!!!”

But then there’s the accidental spammer—the marketing director of a nonprofit who sends an innocent email promoting an upcoming fundraiser, and for some reason it ends up in recipients’ junk folders. Or, even worse, the server gets blacklisted.

We can all fall prey to accidental spamming from time to time. With the huge amount of spam sent on the web (70% of all email traffic), Internet service providers (ISPs) and mailbox providers have really had to crack down on filtering out these annoying emails. 

Today, you’ll learn some of the reasons why you might have accidentally ended up in the spam folder or on a blacklist, and how you can avoid doing so in the future.

But first, let’s talk about the war against spam, and its two biggest enforcers—Internet Service Providers (ISPs) and mailbox providers.

The War Against Spam

So, why are ISPs and mailbox providers so aggressively against spam?

First of all, ISPs like AOL, AT&T and Comcast don’t want spam consuming valuable bandwidth and data storage. Second, mailbox providers (such as Gmail, Hotmail, Yahoo! Mail and AOL Mail) are in a constant battle with spam because they want to protect their users from being bombarded by junk and inappropriate emails. 

ISPs and mailbox providers use several defenses to block out spam:


These email firewalls are used by ISPs to prevent the most obvious spam from ever reaching a mailbox provider.

Spam filters

When spam does get through a gatekeeper, spam filters are set up by mailbox providers to prevent junk from getting into a user’s inbox.

Spam filters determine if an email is spam by looking at a long list of criteria. Each item on the list is worth a certain number of points. For example, a dollar sign ($) in your subject line might earn you one point. The number of points you earn is called your “spam score.” Spam filters set a limit to how many points an email can receive before it is considered spam. If your email exceeds that limit, it’s going straight to the spam folder, where it’s likely to never see the light of day.


ISPs, mailbox providers and other companies use blacklists to identify notorious spammers and block them from their networks.

If a large percentage of your email recipients report you as spam, your server could end up being placed on a blacklist. A blacklist is a log of known spammers’ IP addresses. ISPs and mailbox providers can reference these blacklists to determine which email servers they should block. You can use MxToolbox to see if your email server is on a blacklist.

So, how do you make sure your email campaigns are not mistakenly considered spam by filters and gateways? And how do you stay off blacklists? 

How To Avoid The Spam Folder

spam folderBefore I go further, I want to make something clear—I am not here to teach you tricks for sneaking spammy emails into people’s inboxes. Rather, I am encouraging you to make sure your emails are relevant, useful and valuable to your audience, while also complying with the rules set in place by ISPs and mailbox providers. In other words, send email with integrity.

Keeping that in mind, it’s also important to understand that most spam filters determine your spam score based on three factors: content, engagement and deliverability.


If you have good intentions, it’s likely that your email won’t be considered spam. However, some spam criteria might surprise you. Follow these best practices when composing your email content to avoid getting caught by a spam filter:

  • Don’t use deceptive subject lines. For example, don’t begin with “Re:” to make people think they’ve had prior communication with you.
  • Don’t go nuts with exclamation points!!!!!!!
  • Don’t start your subject line with a dollar amount or talk about a large amount of money 
  • Don’t include spammy keywords like “ACT NOW” or “100% Guaranteed.” (The rule is, if a car salesman would say it, then you shouldn’t.)
  • Don’t write in ALL CAPS.
  • Don’t use colored fonts or an extra large font size.
  • Make sure no Microsoft Word coding was pasted into an HTML email.
  • Never send just an image. Always include text.
  • Don’t send too many images in one email.
  • Check for misspellings.
  • Include your organization’s physical address.
  • Use a valid “sender” email address and “from” name – a real person’s name and email address.
  • Don’t use the salutation “Dear…”

Check out SpamAssassin to see how this spam filter assigns points for different criteria.  


Spam filters also look at recipient behavior to determine a sender’s spam score. 

In Gmail, for example, recipients can click to report an email as spam. Gmail users can also move an email out of the spam folder, if they feel it doesn’t belong there. Gmail takes this behavior into consideration when determining whether or not emails from a particular server are spam.

Spam filters also look how many people are opening and clicking your emails, as well as how many people are deleting your emails without ever opening them. The more positive engagement recipients have with your emails, the better for your email reputation.


ISPs can monitor the deliverability of your emails (basically, how many emails bounce) and share that information with spam filters. Too many bounces can give you a bad reputation, which could lead to a bad spam score. Be sure to check out my last two posts on email list management, in which I discuss best practices for improving the deliverability of your emails. Part 1 explains how to scrub your list clean of harmful email addresses, and Part 2 provides tips for building a clean, high quality email list


Spam reports and blacklisting can be scary; when that happens, all of your email marketing efforts are going to waste. But by understanding how spam filters work and following best practices—and by sending emails with integrity—you can almost always expect a positive outcome from your email marketing campaigns. 


UP NEXT: Choosing The Right Email Marketing Software For Your Organization

Are you in the market for a new email marketing service provider? Come back next week for a guide to shopping for the perfect email software for your organization!


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