SpamAssassin Rules and what they Mean for your Emails

For the past several years I have been following SpamAssassin’s rule set and I am always amazed by how many seemingly innocuous things (e.g. “Dear x”) can make perfectly harmless emails come under suspicion.

The vast majority of issues come from poorly coded/authenticated emails. This can either be the fault of the email’s designer (in the case of poor HTML) or the the platform (infrastructural issue). Some common HTML issues include:

  1. Too much code (in terms of your code to text ratio)
  2. Too little text (in terms of your text to image ratio) — you get penalized for being succint if you also use images
  3. Poorly written code (title set to “untitled”; unclosed tags, etc.) — apparently spammers cannot code well
  4. Larger or smaller than ordinary fonts — stick to something similar to 10-12pt
  5. “Shouting” — too many words in all caps; excessive use of red or blue font
  6. Hiding the unsubscribe text by making the font the same color as the background — a shady practice that would only result in spam complaints anyway



Here are a few highlights that I often see being violated that you would never think about from a SPAM perspective. It is interesting that what is often thought of as a best practice (explaining how/why someone was subscribed  and how he or she could unsubscribe) must be worded carefully to avoid a penalty: 

  1. Email contains ‘Dear (something)’ — so much for being friendly
  2. Claims you can be removed from the list 
  3. Talks about how to be removed from mailings
  4. Removal phrase right before a link

It is humorous though quite sad that email has been somewhat ruined because of all of the bad apples who take advantage of unsuspecting inboxes. Twitter, unfortunately is likely to follow if unchecked.

See the full list of Spam Assassin Rules

Measuring email marketing deliverability

Email marketing vendors often boast that their infrastructure and ISP relations teams lead to high deliverability. While it is true that any ESP is likely to significantly beat a company’s in-house solution, it becomes more difficult when trying to compare one ESP’s deliverability to another.


When you are evaluating email vendors, I highly recommend starting by subscribing to their respective newsletters via multiple email addresses (Gmail, Yahoo!, corporate account, etc.). Then tote whether or not the messages are delivered to your inbox in major email clients. This would seem to be an obvious test but many buyers simply rely on reputation rather than experimentation when making a decision.

Measuring the Sender Score of the Vendors

Return Path, who operates the largest email accreditation service, Sender Score Certified, rates IP addresses by giving them sender scores. The score is made up of several different factors such as SPAM complaints, sending volume, amount of mail sent to unknown addresses. and the IP’s DNS settings. Anything lower than 70 should be avoided. Ideally you want to see something that is 80 or higher.

To find the IP address of the mail server for an email you receive, you will need to see the message’s original headers.

In Gmail for example, click on the downward arrow on the top right of an email. Then select “Show Original” to see the message’s headers. You can then see the IP address of the sender and check it here. You will be surprised by how many low scores you will find. You can do this in a similar manner with Yahoo! Mail and other major email clients.

Checking Email Authentication

The header also gives you other useful information such as whether or not the emails pass various types of authentication. ISPs and corporate filters use some or all of the four major authentication frameworks to help classify email. Most email clients will allow you to check your incoming emails to see if they are authenticated. Gmail for example will tell you whether or not the email passes SPF and DKIM authentication. Simply do a find for “DKIM” when viewing the header. The more levels of authentication your ESP uses, the better the deliverability is likely to be.

There is of course a lot more than deliverability that goes into an email service provider evaluation (feature set, ease of use, services component, etc.) but this should at least give buyers an objective to way measure one of the more esoteric aspects of email marketing.

Is a dedicated IP address right for me?

A dedicated IP address is not the ideal solution for everyone. There’s agreat article on that discusses the pros and cons so you can decide whether a dedicated or shared IP is right for your company.’s overall recommendation is that marketers that frequently send large numbers of email blasts would benefit from a dedicated IP address, while those that send only occasional or monthly emails would probably not want a dedicated IP address. Below are some of the highlights from the article:


  • Reputation – Sharing your IP address means you’re also sharing your reputation. Having your own dedicated IP address puts you in charge of your reputation and deliverability.
  • Accreditation and Whitelisting – Some whitelisting programs require you to have a dedicated IP address. Being accredited can help improve deliverability.
  • Monitoring – Being in charge of your own IP address allows you to monitor and take action immediately on any issues that arise.


  • Volume Spikes – Spikes in volume can negatively affect your reputation and need to be watched and managed carefully. Since your IP address is dedicated to you, you wouldn’t have your ESP balancing out the spikes with other clients’ mailings, so this would be your responsibility to manage.
  • Volume History – Reputation is also tied into volume history. Since you’re starting fresh with a new IP address, you would not have any history. Some ISPs are throttling IP addresses with no volume history to stricter reputation standards, so your reputation would need to be built slowly over time.
  • Deliverability – Having your own dedicated IP address doesn’t automatically mean your deliverability will be better. To improve deliverability, you also need to become accredited with whitelisting companies.
  • Monitoring – Monitoring and taking action on issues that arise requires both time/effort and money.
  • Cost – Most ESPs charge extra for this service (as a separate line item cost or added to monthly fees). Additional costs can be accrued from whitelisting and monitoring (direct costs to your ESP or costs incurred from taking the time and effort to monitor yourself).

Creating HTML Emails Everyone Can Love

One of the constant challenges for marketers is creating HTML emails that work with everyone’s inbox. There are some commonly known tips and tricks for creating effective emails, but there is no hard-and-fast rule book. Today MarketingProfs posted an article reviewing common issues marketers face in building their emails. Many of these items are ones I’ve discussed before in this blog. Here are some that I found most valuable:

  • Around 600 pixels wide is about right for emails
  • Don’t use external CSS for formating. Some programs, including Microsoft Outlook 2007, don’t support CSS.
  • Avoid flash.
  • Test in multiple email clients, if possible. Don’t forget to test on mobile devices as well.
  • Be aware that not everyone loads HTML. Use alt tags for those who may view text only emails or are using a mobile device.
  • Use fully qualified links. Remember that using something like <img src=”images/headline.gif”> may look fine on your internal servers, but it won’t render externally.

One of the best ways to spot-check your templates is to send the email to a small test list of colleagues or trusted partners. As with proofreading a paper, this will ensure that you don’t miss anything. It’s easy to brush over details if you’ve been staring at the same email for too long. It also allows you to gather feedback and see your email from a different perspective, making sure you don’t get tunnel vision.

The Trouble with Buying an Email List

I have talked often about the fine line between permission based marketing and spam. Another component of this is how you build your lists.

Many marketers see purchasing a list of names as a quick way to start out an email marketing program. One of my favorite articles from Email Marketing Reports explains why, as with most “get rich quick” schemes, this is a poor substitute for growing a list organically.

Buying v. Renting
Buying a list is different than renting a list. Renting a list is a common and widely accepted practice by email marketers. Renting a list means paying a fee to sponsor an email blast to a list of subscribers, for example, participating in a White Paper of the Day mailing. When you rent a list, you never have physical possession of the list. When you purchase a list, you are receiving a copy of the list with the assumption that you are free to use the list as often as you like.

Why Not Buy?  
It is considered a best practice to clearly inform people of what they are signing up for when they are put on a list. If you are buying a list, the people on that list have no reason to expect a message from you, and certainly haven’t given you permission to send it. These are not prospects who are interested in building relationships with you and your brand. It is likely that you will experience extremely high opt out rates with purchased lists, and in many cases recipients may even flag your message as spam.

Brownlow’s Email Marketing Reports article also points out that marketers work hard to build and nurture their lists. They want to ensure that the prospects on their list remain happy with the email program they provide and are not bombarded with spam. Therefore, as Brownlow states simply:

“Clearly, no self-respecting list owner is ever going to sell copies of their address list. Not if they want to preserve its value.”

Better safe than sorry. Start by building lists through trade shows, sponsored blasts, registration on your website or other legitimate means. You will wind up with a more valuable set of prospects and prevent problems like blacklisting, which will inevitably cause more stress in the long run.


Oversending as an Email Marketing Tactic

Oversending: an outgrowth of the old “send until you break even” direct mail model. Combine this with the low-cost nature of the email channel and that’s a lot of emails. Repetitive messaging may be a “do” in marketing, but repetitive sending is a “please don’t” which is often formalized by the dreaded “mark as spam.”

The belief that sending more emails to more people leads to better business is flawed. After a certain point, this approach will lead to a greater amount of unsubscribes and spam complaints, resulting in higher acquisition costs to replace the lost customers.

The solution? Segmenting prospects and nurturing them through appropriate drip marketing programs. A more personalized and targeted approach is key in driving sales and conversions while reducing list churn.

Open Rates are Open to Interpretation

I highly recommend you click over to Tamara’s recent post on open rates at BeRelevant, an email marketing blog, for a quick and easy explanation of how open rates are calculated.

I frequently speak with marketers who aren’t aware that open rates are based on images being loaded or that they can’t be tracked at all for text-only emails.  These facts make open rates a highly unreliable marker of success – and it’s likely that if you’re presenting these numbers to your boss, you’re actually selling yourself way short!