Curated by: Luigi Canali De Rossi

Saturday, May 24, 2008

Spam Checking Tools And Tips To Avoid Your Newsletter Being Filtered, Blacklisted Or Marked As Spam

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Sending out email newsletters and having them delivered reliably to your list of subscribers has become a greater challenge than I would have ever thought. Problem is, if you don't devote yourself to it, everything is set for your email newsletter to run into trouble. To not run into such issues, you really need to proactively do something about it. The negative consequences are blacklisting of your email newsletter and having your email newsletter filtered out by spam filters on your recipient ISP mail server or on their computers.

Photo credit: Tyler Olson and Yong Hian Lim mashed-up by Robin Good

I have seen my own email newsletters, which contain no spam at all, beaten down by blacklisting servers and spam filters like they contained radioactive substances. I have also seen thousands if not ten of thousands of email subscribers being lost to these same supposed gatekeepers.

It's a bloodshed, unless you take some proactive action to prevent this from happening.

Anti-spam filters catch every single email arriving to your inbox before it is actually delivered to it and do a full spam check on it before you can even see it.

Such spam filters use a scoring system to classify an email as a legitimate message or as spam. Some of the most popular among these spam filters, such as SpamAssassin, SpamCombat or SpamProbe are designed to look for specific patterns in your email messages and to assign "spamming points" to them when they encounter such pre-defined patterns.

These patterns or spam-signatures may actually include anything from the specific words you use in the Subject line of your newsletter to the actual words inside the text, specific phrases, images, to the format (HTML or text-only) you may have chosen for the delivery of your newsletter, and even to the type of colors you may have used.

Depending on the amount of such "spam" patterns these filters find inside your email newsletter, the spam filter will assign a specific score to it. If your overall spam score goes beyond a preset threshold your newsletter is marked as *spam*, the *SPAM* or *JUNK* word is sometimes pre-fixed to the subject line of your newsletter and then sent to your spam bin automatically.

This is why, one of your main concerns if you are an online publisher sending out an email newsletter is to think well ahead of time about these issues and to do everything possible to avoid falling in such possible email spam filter traps.

Here some personal advice and my selected toolkit on how you can prevent your email newsletter from getting trapped inside spam filters and blacklists:


What To Check To Prevent Your Email Newsletter From Being Filtered, Blacklisted or Marked As Spam

1) Newsletter Subject Line

Edit carefully your email newsletter subject line. This is one of the most sensitive areas. Watch out what you do here. Some no-nos are words in all caps, the word free, lots of white spaces, name or email of recipients, the use of a date. But there is a lot more. The best way to avoid any risk is to have a professional title that doesn't use any catchy words.

2) Subject Line Capitalization

Capitalizing word initials or worst, whole words inside an email newsletter subject line is sure to get you in some trouble. Avoid capitalization at all costs and you should have no problems with spam filters.

3) Spam-like Content

Avoid utilizing phrases that may appear as spam-like to email spam filters. Sentences like "Click here!" or "Once in a lifetime opportunity!" or simply exaggerating with too many exclamation points!!!!!! can hit the sensitive triggers of many of the popular email spam filters.

4) Text-Based Is Better

Make it look like text. Email newsletters are generally of one of two kinds. Text-based and HTML-based. If you want to increase the spam safety and accessibility of your newsletter text-based is the safest solution. Even if you choose to go the HTML route, make sure you format and layout your newsletter content "to make it look like" it was in fact a text-based one.

Also: Do not send your HTML-based newsletter without a text-delivery option. If your email newsletter is in HTML and it doesn't automatically switch to text-format for those readers who can't receive HTML, it will get filtered out.

5) Attachments

Don't send attachments. Attachments often carry viruses. In defense, they are frequently filtered out proactively. Even if an attachment gets through to your readers, it is a burden to expect them to run it through a virus protection program.

6) Bcc Field

Avoid using Bcc distribution to more than a few recipients. If you use lots and lots of recipients inside your Bcc field it is very likely that your email newsletter will be marked as spam.

7) Color Use

Avoid playing with colored text to get your message across. This is a bad practice from all standpoints as, unless you change background, black remains the most legible color on your screen. Red emphasis is highly connotated with tricky marketing schemes and spam email and also other colors like green or blue should be avoided at all costs. If you want to really hit the nerves of major spam filters change the color of your email background and you are in for "national disappearance day".

8) Newsletter File Size

Put some real meat inside your newsletters. The file size of your email newsletter does matter to anti-spam filters. Keep message size between 20K and 50K. This is because the majority of spam emails weight-in most of the time at less than 20K.

9) Bad HTML Code

Make sure you are not creating your newsletter by utilizing bad HTML code generated by popular tools such as Microsoft Word. If you create your newsletter in Microsoft Word to then save it as HTML you should be aware that the code generated by MS Word and other tools may be very "unorthodox" and this is one thing that email spam filters really do not like.

10) Use of Trigger Words

Do not use spam trigger words., which offers an online publishing system to would-be online entrepreneurs, provides a free email marketing tool called SpamCheck. In their recommendations, SiteSell experts say that you should strongly avoid using evident spam-trigger words such as "free" inside your email newsletter. Using such spam-trigger words in combination with other trigger words such as "trial", "quote", "sample", "access" can really make your newsletter inaccessible to most anyone who uses a spam filter of some kind.

Subject Line Trigger Words Sheet (PDF)

Words and phrases that trigger spam filters

20 Words That Kill - At Least When It Comes to Spam Filters

11) Images

Do not use images inside your newsletter in place of the text. Some publishers may choose to use a large image to display the contents of the whole newsletter as it may contain lots of visuals and graphics. While the intent is laudable the results may often be nothing to tell your friends about. Avoid using large images like wildfire and stay as text-based and humble of image use as possible.

12) Virus Free

Ensure always that your computer as well as your network are virus free. With laptops coming and going from your LAN, friends hooking in, and open wi-fi connections it is wise to have in place tools and procedures to make sure at all times that the stuff you send out is fully virus- and other malware-free. You certainly want to avoid to inadvertently send out a virus you have on your machine together with your own newsletter and name.

13) Removal

Make sure that your newsletter always includes an easy means for your subscribers to easily remove themselves from your distribution list.




One key critical element that is often overlooked, is the understanding that the server you are using to send your email newsletters plays a vital role in determining whether or not your newsletter will reach its supposed recipients.

The problem stems from the fact that many of the newsletter delivery services out there, have been used by some spammers or other and therefore such servers have become blacklisted. Imagine therefore what happens when you send your email newsletter through them. Among the top priority things you need to do when you evaluate your newsletter delivery service is to see whether they have been blacklisted.

If you have never heard of the word before, "blacklists" are databases of known spammers that ISPs regularly check.

It is possible to be added to a blacklist without being informed by anyone. It takes simply for a recipient in your email list to mark your email as spam to start a process, which can eventually get you fully blacklisted.


Good Strategies To Prevent Blacklisting

1) Double Opt-In

Use always a double-opt-in method for signing-up your newsletter readers. Any other approach is a recipe for trouble.

A few years ago I was not convinced myself of this and let direct opt-in rule only to lose half of my subscribers in a few months once key mail gateways started blacklisting me because of this practice.

The double opt-in approach simply involves the automatic sending of an e-mail to those who sign-up for your newsletter (after they have opted in at you site) asking them to confirm (via a simple click) that yes, you have permission to send them your newsletter in the future.

2) White-Listing

This is as simple to say as it is hard to get it to have an impact on your readers, but if you are persistent and clear enough in your communication with your subscribers you should positively ask them to add your newsletter "From" email address to their address books or to white-list it. Tell readers on your newsletter sign-up page and in your confirmation email, from what "from" line and domain your emails will be sent. Ask them to add this data to their "safe folder", address book or whitelist of approved email senders.

Also, you can add a blurb at the very top of your newsletter that reads something like this:

"To ensure you will not lose any of my future updates due to a spam filter error please do add to your address book or "safe-senders" list."

3) Ask Your Subscribers

Last but not least. If you hear from subscribers who are not receiving your newsletter, ask them to look in their spam or junk email folders. If they find your newsletter there, ask them to kindly set-up an automatic filter that takes care of sending your newsletter directly inside their inbox.

All of these actions will guarantee that your newsletter will not have to pass through your recipient anti-spam filters.


Has My Newsletter Been Spam Filtered? How Do I Tell?


An easy way to tell whether your email newsletter has been blacklisted or spam-filtered is to look at your "open rate". This is a metric, that when provided by your newsletter distribution service, allows you to see how many people are actually opening the email containing your newsletter.

The average "opening rate" for an email newsletter is 20% to 30%. If the open rate suddenly drops below your standard levels, you probably have a spam filter problem.

Fast declining number of subscribers. If all of a sudden your email subscribers are dropping instead of increasing, while the quality and content selection for your newsletter has not changed, you can be sure that spam filters and blacklisting have arrived to your party.

High bounce rate is another relevant indicator. Look through your hard bounces, that is email recipients you have not been to reach and dig into the SMTP replies you have received.


Email Newsletter Spam Checking Tools


Here is the best part of this short guide. Find here below my selection of email newsletter spam-checking tools that you can use immediately, and at zero cost, to verify your next ezine issue:

  1. Spamcheck by SiteSell

  2. Content Checker by Lyris

  3. Spamcheck

  4. Programmer's Heaven Spam Checker

  5. MailingCheck - SpamAssassin Spam Checker software


Selected Tips On Email Newsletter Blacklisting

Some great tips to be found also in these articles:

Originally written by for Master New Media and first published on May 24th, 2008 as "Spam Checking Tools And Tips To Avoid Your Newsletter Being Filtered, Blacklisted Or Marked As Spam"

Robin Good -
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posted by Robin Good on Saturday, May 24 2008, updated on Tuesday, May 5 2015

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