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E-mail Marketing - The Content

11 min read



E-mail Marketing - The Content

As you send e-mails to your customers, their mailbox providers (ISPs) will check your reputation as a sender as well as your e-mail content. The mailbox provider will then either place it in the inbox, send it to junk or spam folders, or even block it completely. While this depends on several factors and different protocols mailbox providers use, one important aspect is content. It’s all for a good cause, to fight spammers and keep one step ahead of them. We have summarized the latest best practice so that your e-mail will pass with flying colors!

Table of Contents


Despite all the great new channels, tactics and technology, e-mail marketing remains one of the main campaign tactics used in most countries around the globe. E-mail marketing is often an underestimated channel leading to an inefficient usage of it.

In the article Welcome to E-mail Marketing we have already introduced you to the basics of e-mail marketing. Now, it is time to dive deeper into e-mail content.

Mailbox providers have come to know the behavior of spammers and senders of unsolicited e-mail. The usual suspects employ a typical style of building content which is then sanctioned by mailbox providers. This article aims to help you to avoid these pitfalls while showing you how to increase your content quality to appease mailbox providers. On the other hand, writing a great e-mail copy is an art and this article won’t go into what constitutes the perfect e-mail that will drive engagement and ultimately sales.

At the time of writing, we have gathered the latest information to the best of our knowledge. However, as mailbox providers and spammers carry on their war dance, this article can only serve as indication. Below you will find hints on how to always stay up to date.

Content Checklist

We have listed a few things to look out for during content creation. Use the checklist to validate your e-mail components and ensure your content will survive the checks of mailbox providers:

Component Recommendation

Subject Line

In general, the subject line mustn’t be misleading, that is it should accurately reflect the content of the e-mail. Avoid overusing uppercase and excessive punctuation as well as specific words that trigger spam filters. Furthermore, exclamation marks and fake Re: or Fwd: prefixes will get noticed by mailbox providers. Keep subject lines to 40 characters or less. Personalize the subject line and use pronouns to suggest engagement. The same applies to pre-headers, also known as snippets or Johnson Boxes.

Text Format

Avoid colorful fonts or backgrounds, flashy design, and uppercase as much as possible. Try to break up the text into readable chunks, instead of one long paragraph.


The copy should not contain any spelling or grammar mistakes. Use spell-check tools and ideally native speakers to proofread your e-mail for style and grammar. Finally, avoid words that will trigger the spam detector of the mailbox provider. You will find language specific lists online.

Call to Action and Offers

Sell the offer, not the product. There should be one offer and one call to action (CTA), that is repeated in the e-mail. If you are using CTA buttons, ensure they aren’t too flashy and avoid spam-like copy such as 'CLICK HERE!'. Your CTA should be placed above the fold (the top part of a web page that is visible upon load). Offers should be specific and tangible.

HTML Quality

Avoid badly coded HTML and syntax errors showing up in the text.

When testing e-mails, also check their display on other devices and browsers, as the number of people reading e-mails on mobile devices continues to grow, including low-end devices.


In general, try to keep links to a minimum. If you use them, ensure that they all point to the same domain. Similarly, domains used in all the links should match your sending domain (sender profile and reply address). If you want to use third-party URLs, check their reputation before adding them to your e-mail, as they may impact your e-mail deliverability. Furthermore, you should make sure that the linked text directs to the actual web-page that it points to.

Avoid raw links that spell out the entire URL and instead hyperlink the text. This is seen as more descriptive for the reader, enhances the readability, and as such will generate more clicks.

When using a URL shortener, please make sure to use a custom domain and not the generic domain. The generic domains are also used by spammers and therefore are often blocklisted.


Set meaningful alt tags for images that include your subject line or headline.

Text to Image Ratio

Because mailbox providers check for specific keywords to indicate whether or not an e-mail is spam, e-mails without much text will raise suspicion. To convey their message, spammers use images, which is why it is important to avoid image-heavy e-mails and ensure text outweighs images (approx. 70:30). Also, consider those recipients who have turned off image download and will only see a blank e-mail with no text. Apart from your customer not understanding what is being conveyed, mailbox providers will mark these large images as spam content.

Video, JavaScript and Flash Content

If you need to use rich media content, make sure you test it well before send-out. Alternatively, consider using an enticing image or text with a link to rich media on your website.

Attachments On the whole, attachments should be avoided.
Message Size

Messages over 100 kb in size get blocked more often. Aim for 35 to 75 kb.

Sender Address No-reply sender addresses imply you don’t want to engage with the recipient. This is not seen as favorable by mailbox providers, which is why you should use a more customer-friendly valid sender e-mail address that identifies your business, such as ''. Once you have selected your sender address, stick to it.
Consistent Branding

Ensure your branding is consistent throughout your e-mails. Recipients will recognize your e-mail leading to higher engagement and lower by complaint rates. One way of achieving a high degree of consistency is to work with footer and header templates.

Data Privacy Policy Clearly communicate your data privacy policy.
Legal Considerations Validate you are adhering to applicable anti-spam and privacy laws and policies in your region.
Unsubscribe Option

In a short text, remind subscribers where they opted in to receive your e-mail in the first place. Also, let them know how they can opt-out. Unsubscribe and opt-out links should be prominently placed, ideally above the fold. Even if it seems counterintuitive to make it this easy to unsubscribe, it will benefit your reputation in the long run. Learn more about permission in the article Introduction to Permission Marketing.

Be Relevant

As we have learned in the introduction article to E-mail Marketing, relevance is the key driver for engagement and for high inbox placement rates.

Relevance can come in different shapes and sizes. A few core aspects are the following:

  • Audience of one: One way to make the content more relevant is to target and personalize your message to the individual recipient.

  • Timing: Another way to make the content more relevant is to find the best timing of your message. The kind of e-mail campaign as well as the recipients country of origin has a high impact on their daily or weekly time slot to open up e-mails. You will find studies online that will tell you the best timing or even better use the SAP Marketing Cloud 'E-mail Sending Time Score' to automate the best sending time selection.

  • Incentive: Put yourself into the shoes of your recipient and ask yourself 'What is in for me'? If you're unable to answer this question, very likely you should go back to the drawing board. Each message needs to have a clear incentive for your recipient. A reason to open up the message and ideally even use the CTA.

  • Journey: You should look at every e-mail as one step of a journey and not as a one-off action. If you manage to provide a holistic experience, you will be able to increase your inbox placement rates as a whole. If you need ideas on how to do so, please follow our approach to ideate campaigns with design thinking. A step-by-step guide can be found here.

  • Look at the data: This goes without saying, but look at the data and find out if your content was perceived as relevant or not. If it was not, make the appropriate adjustments and improve the content relevance. You can also automate this process by using A/B testing. SAP Marketing Cloud can help you. Follow this link to find out more.

Useful Tools

In last chapter, we have learned that SAP Marketing Cloud can support us with the challenges of being relevant. Also, we need to stay focused on the message content. The checklist above is a good indication on what needs to be done, but it is challenging to stay up to date on all potential checks that should be performed.

To stay ahead of the curve, we highly recommend to rely on specialized service vendors who will help you with the content checks. We typically work with Litmus for this purpose.

Image one: This screenshot from Litmus' checklist service shows an assessment of an e-mail preview text

How does Litmus work? Ideally, you jump to their page and follow the guides in the resources section. The super short version is that you either copy-paste HTML or use a test e-mail address to submit your e-mail draft to 'Checklist' (see also image one above). Starting with the "First Impressions" section, this service checks the e-mail components such as links, images and more. Based on best practice, Checklist then flags issues as shown above for a preview text. A status is given as well as an explanation with useful tips on how to improve the e-mail. Once you have resolved the issues, a preview will allow you to check how your e-mail would fare on different devices and clients.


While mailbox providers are strict and their rules constantly change, our checklist and recommendations will help you to keep your inbox placement rate high. Interested to learn more? Then, please make sure to do a deep dive into all of the aspects of becoming an e-mail deliverability hero:

You might also want to go one step back to learn about the essentials of e-mail marketing in "Welcome to E-mail Marketing".

In case you need further support, please refer to our dedicated 'E-mail Deliverability Guidance' service. You will find more details in the fact sheet that is linked in the services section of this article.