The best way to judge an email message is whether it achieves its campaign goal. But even the most effective email can end up in many a recipient’s spam folder, or an email client could mangle the creative. Here are eight best practices that can improve your email marketing results.

Tom Buchok, director of product, MailCharts

As the data provider for the IR 1000, MailCharts gets a behind-the-scenes look at thousands of email messages sent every day by retailers all over the world.

Each email generates dozens of data points, which we use in a unique scoring system allowing marketers to assess the quality of their emails, compare their messages to the competition or search for creative inspiration.

The top score any email can achieve is 100%, meaning it passes eight important criteria. What does a 100% email look like? Before we show you, let’s see take a look at the criteria.

How email scoring works


The best way to judge an email message is whether it achieves its campaign goal. But even the most effective email can end up in many a recipient’s spam folder, or an email client could mangle the creative.

A good rating system should call out these potential problems. It should score email on current best practices in email design and function. The more best practices it follows, the better.

An email that flunks one quality check probably won’t get flagged by an ISP or a spam filter. But the more best practices it fails, the less likely it is to reach subscribers reliably or effectively.

Here’s what the score looks like when you call up an email in the MailCharts database. You can see right away which tests it passes and which, if any, it fails.

MailCharts score

The 8-point rating system

MailCharts uses these criteria to score each email:

1. Inbox friendly subject line

Most email clients cap subject lines at 40 to 60 characters. Although marketers debate whether longer or shorter subject lines convert better, in general, a shorter subject line along with optimized preview text will drive more opens and conversions. (See No. 3 below.)

2. Optimized for mobile


Because more than half of all emails are opened on mobile devices, it’s essential that your email render correctly whether your customer reads it on a desktop, a phone, a tablet or a smartwatch.

3. Optimized preview text

This text is the first line of copy in the email message. Many inboxes pull that first line into the inbox next to the subject line. Optimized preview text complements the subject line, adding or reinforcing information such as a call to action, the email offer, deadline or other key information.

4. Reply-able return email address


[email protected]” or “[email protected]” is a big subscriber turn-off. (It doesn’t stop them from replying, either. They’ll just get mad that you’re ignoring their emails.) “Help@” or “customerservice@” email addresses are more customer friendly.

5. Gmail-friendly HTML weight

Gmail might be the bane of your email-marketing existence, but it’s running neck-and-neck with Apple’s iPhone email app for global email market share. So chances are pretty good a big chunk of your subscriber base is using it.

Gmail cuts off emails bigger than 102KB of HTML. The HTML is the code used to show images, font colors and provide structure to your email—if that code is too heavy and it causes clipping your message won’t be shown. (We’ve also seen evidence that open pixels get clipped, causing a headache for marketers trying to figure out why their open rates took a nose dive!)


6. Sensible image weight

Large images totaling 800KB or more load slower, especially on older hardware or slower data connections. That creates a poor email experience and inevitably reduces clicks or conversions.

7. Passes DKIM and SPF checks

DKIM (Domain Keys Identified Mail) and SPF (Sender Policy Framework) are authentication protocols that check whether you are an authorized sender or a spammer spoofing your email address. Fail this check and will almost assuredly be blocked or routed to the spam folder.


8. No spammy content

Although sender reputation and verification are becoming more important in identifying potential spam, ISPs still use filters to trap spammy-looking emails with misspellings, single images without text, all-caps copy or crazy punctuation (too many !!!!!!!!!!s, for example).

Who’s a 100-percenter?

All five emails below are from senders in the IR1000, and each one scores 100% in our rating system.

This score can change with every email. Scores for even some of top emailers range from 50% (ouch!) to 100% depending on the makeup of each message.


What these five emails have in common:

  • They’re streamlined to a single column with few siderails and simple navigation. No complex navigation bars, no lists of links, and they don’t scroll forever.
  • Each one has a strong subject line-preview text combination. For instance, Sleep Number’s subject line “It’s time for amazing sleep! Take 50% off …” segues nicely into the preview text “our Limited Edition smart bed PLUS special financing.”
  • They use images sensibly. They balance images and copy. While some come close to the Gmail clipping point, they don’t exceed it.

Click on each link to see a larger version of the email.

Sleep Number emailSender: Sleep Number URL:

Lego UK email

Sender: Lego UK URL:

Columbia email

Sender: Columbia Sportswear Rewards URL:

Home Depot email

Sender: The Home Depot URL:

Gilt email

Sender: Gilt URL:


Wrapping it up: Do email scores really matter?

Does it matter how your email campaigns score on our—or anyone else’s—rating system?  We happen to think it’s always valuable to use recognized best-practices criteria to be able to benchmark one email program against another. Email scores give you common ground to assess the quality and functionality of your emails and those of your peers and competitors.


Knowing how your emails compare with your competition—not just in your niche of the market but across the entire spectrum of emails within your subscribers’ inboxes—will help you create more useful, more concise, and more reliable email messages.

All of which translates into a stronger email program!

MailCharts provides competitive intelligence for email marketers.