Marketing Templates How-to
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03 June 2018

How to Avoid Spam Filters When Sending Emails

Stripo / Blog / How to Avoid Spam Filters When Sending Emails

Why do emails go to spam? Three pillars of email deliverability are domain reputation, email content, and relevance of content.

According to AccuWeb research, 23% of emails of total spam complaints are reported as spam because of email content. Just think that every fourth email of those that did not pass email spam filters does not reach its goal, and ruins your reputation due to its content.

Definitely, the rest 77% depend on other reasons, but we are about to focus on improving the content to decrease spam complaint rate and improve the deliverability of your future emails.

Email spam-proof content

First off, I need to remind you that email content is divided into three groups:
     ● copy;
     ● design;
     ● technical features.

Here, we are going to name a problem and suggest a way out to prevent emails from going into spam folder by using Stripo or any other editor.


No matter how good or untypical your email design is, text performs the most important mission in newsletters.

The text message itself

Text matters a lot when it comes to email subject lines.

If you want your messages to be delivered into recipients’ inboxes, then you:
     ● should not use all caps in the email subject lines;
     ● make them catchy, engaging, persuading.


This doesn’t look like an email I can trust. I did not even dare to open it.

Make sure you always use web-safe fonts and appropriate font size to make your emails legible. Let your customers feel cared about and cherished. If they have to zoom in to read your value proposition, your messages are likely to be deleted no matter how generous the proposition is.

Irrelevance of email content

When the subject line says “Read world’s latest news”, and inside the email, a recipient is asked to buy something, he or she is likely to mark this message as spam.

Email content should comply with the subject line.


The design of email newsletter is the face of the entire company. Pay very close attention to it.

Image-to-text ratio

Along with sticking to all recommendations given here, you should always remember about the image-to-text ratio. This is the golden rule to follow in order to pass all the anti-spam filters. Some spam testing tools still argue about the most effective coefficient. But they all agreed that 80/20% is the minimal proportion. More text in emails is preferable, while less is unacceptable.

So, can Stripo really help you here? Yes, it can. Our editor allows using background colors or images for every text block. This way, unlike images with inscriptions created in a photo editor, all your texts will be recognized by email clients.

Now you may enliven your text emails with colors and images.


So, in this example, I set a background image, and as a fallback a respective background color for the entire structure. Here is what I got: my email contains text, is definitely legible, and hopefully spicy.


Please be advised that all the texts you have written on a banner will not be considered as a text, it will be considered as an image element.

How can you check if your ratio is within norms? I use Mail-tester. You may try out another spam testing tool.


It happens very often that you need to separate two blocks or structures to make your email more legible and elegant. And here rises an issue: spacer is an image. One more image in your template does not sound really good.

Our spacers will help stay within image-to-text ratio norms and avoid spam filters when sending emails as our horizontal dynamic spacer is a symbol but not an image.


Interactive elements

These elements are the hottest trend for 2018; they are meant to spice up your newsletters and are currently passionately talked about at numerous email marketing summits. More and more companies develop various kinds of interactive elements. You can easily create and modify them with some special tools. But hey, are all email clients ready to deliver them? Well… Only some. Why so?

Some email services are technically not able to transfer and display those elements, so they block these elements or just show them as non-interactive images; while others, by the way, identify them as spam. Consequently, it ruins your reputation.

How can you change this situation for better?

Rule 1 — stop using <i-frame> tags. Gmail delivers them a few times to your customers’ inboxes, but if you keep sending them too often, this email client may mark you as a spammer. <i-frame> is mostly used for embedding videos. The good news is that there is an alternative — you may just insert the link to the video. An editor will show the preview image, so visually it will look like your video is actually embedded into an email.


As you can see in the example, this video has a name and an alt text. They both were added automatically by the editor.

Rule 2 — avoid using JavaScript elements in emails. Currently, they are all considered spam.

Rule 3 — whenever and wherever it is possible, replace interactive elements with theirweb-safe alternatives. These latter are easily implemented with some responsive email template builders which provide their users with email open HTML code.

Rule 4 — if you still decide to entertain your consumers with interactive elements, be it email surveys or image carousels, just make sure you use one element at a time.

Click rate

Yes, this feature may impact your email reputation negatively, as the less subscribers click, the more chances not to pass blocking spam systems.

The less people like your content/value proposition, the less they click. It means that you send irrelevant content. Email clients know about it.

But it happens very often that recipients like what they read, but they do not see any buttons or links to click.

And even here we can help you. With Stripo, you can make big bright buttons that are pretty visible and legible. It is strongly recommended adding links to every image, brand’s logo, and other extra elements, because sometimes customers may click a banner or a product’s card image to get to your website to go shopping.


Unsubscribe and manage preferences options

One more way to keep your emails from going to spam is adding these options to all of your emails. For some dear readers, it may seem that I mentioned these links here mistakenly. No, I said it. Some recipients mark you as spam when they do not see “unsubscribe” button.

The best solution here is putting it in a visible place, making it bright, contrast. Once your customers are no longer interested in your emails, they will just unsubscribe. Don’t force them to mark you as spam.

Note: make it a single opt-out. Subscribers do not need to click too many buttons or confirm anything if they wish to stop receiving newsletters from you.


Or you can make it funny like Chubbies:


Not only is this crucial to help you pass all spam filters, but also is a requirement by the GDPR rules that came into effect on May 25, 2018.

If you do not want your customers to unsubscribe, suggest that they update their preferences — they might be interested in a more relevant content. This option may save you some loyal clients.

The best solution to stop emails going to spam is applying both buttons in your emails’ footer like Pepsi:


Important: keep the weight of email HTML code below 100 kB. If it exceeds this norm, email clients are about to clip your email and add a button “view entire message”. Users don’t have time and desire to download anything. Email client cuts off the bottom part of your emails, thus recipients may not even see the “Unsubscribe” or “Manage Updates” buttons, and will definitely click “Report spam”.

Technical features

The design stands for the visual elements, while technical features make it possible to set, transfer and display these visual elements on customers’ screens; and help us pass anti-spam filters.

Alt text

The absence of alt text can be literally catastrophic for an email.

Because when an image is blocked by an email client, the alt text tells the subscribers what that picture was supposed to show.

Moreover, the alt text performs one more useful mission — it helps your emails to pass email spam filters.

Did you know that all email clients scan emails for the very alt text as they cannot “read” the images? If there’s no alt text detected in your newsletters, email clients may consider it as spam.

Your newsletter emails with this feature are likely to pass those filters.


Keep calm: you can easily add them to images with Stripo. Once you've uploaded your image, in the settings panel you will be asked to enter your "Alt text".

Adding Alt Text to Images

Broken links

Google says that broken links may not cause any harm to your business, or email deliverability. Ok, let it be so. Yet, they cause frustration and can be really annoying. When clients click the magic button to get from an email to your website or read detailed information on a specific topic and see “error 404”, they are unlikely to trust you any longer and are pretty much likely to mark your email as spam.

Definitely, if your emails are short, you can test all the links manually by yourself. In case the email is too long and contains a big number of links, you should use special spam testing tools. They check your emails for broken links, as well.


Domain spam-proof reputation

Now that you know the ways to avoid spam filters by creating proper email content, I want to remind general yet highly important metrics that help your emails pass anti-spam filters.

Brand identity

Brand identity? Yes, your brand logo, company’s name, and the sender’s ID. I would like to start with this feature.

Some time ago I read on the web, that if the company name is made up and there is no such word in the dictionary, your email might not pass spam filters.

I contacted our ESP, and they conducted a research. So, the expert answer is: if the company’s name is mentioned as the sender’s ID, and this name is registered as a domain, there won’t be any problem at all.



This is my favorite logo and company name combination:


When a company becomes as famous as Nike, only logo may remain in its emails ? 

Don’t hesitate to use your company’s logo and name. Subscribers need to get used to your brand.

Double opt-in

Once you get a new email address from your offline visitors, or online ones, do not waste time — send an immediate request to verify the email address and to confirm consent to receive your newsletters. Implement double opt-in!

Firstly, double opt-in helps you stick to all the new GDPR rules as you will have a written consent given by your new subscribers. When needed, you will be able to show this proof. Secondly, when sending emails that request to verify e-addresses, you may notify your customers about how often they will receive your newsletters, and what it will be about. Thirdly, you check if the email address is correct and does not contain any typos. This means it will not go to “Black list” folder.


You can create e-address confirmation emails by using Stripo email templates.


Emails that are sent frequently bother a lot. Emails sent seldomly allow the customers to forget you; and when you finally decide to remind people about yourself again, they may mark your message as spam, unless they are your staunch fans.

Case 1. Sending emails too often

Let’s say you receive promo newsletters two-four times a week. Will you read them all? No, let me paraphrase… Will you like it? Definitely, no. In addition to it, you are about to get a few event-triggered emails the same day if you have bought something from this online shop. Sounds a bit irritating. That is why you should be looking for an ESP that provides the following feature: Annoyance level. eSputnik lets you set a desirable number of emails sent to a client per week. It is recommended not to overcome four.

This screenshot shows that I received 4 emails in four days from Adidas. I can tolerate this, however, the fifth one would certainly be superfluous.


Case 2. Sending emails too seldomly

Reaching out your customers too seldomly or not on a regular basis won’t actually prevent your emails from going to spam either.

The best solution is sending them out on the same day of the week and at the same time. For example, every Thursday at 10 a.m. Make sure you are about to share some relevant information.

One of the several reasons why you don’t send email newsletters on a regular basis yet is that you do not have enough time for creating new emails every time you are starting a new marketing campaign.

Stripo offers a solution — our Library of Content Blocks. You can save your footers, headers, menus, products’ cards with replaceable links, etc. to it. This feature saves you tons of precious time. Whenever it comes to creating a new campaign, you just drag-and-drop this element from the library into your new email. Thus, it won’t take you longer than 10 minutes to create a brand new professional email template.

For your convenience, you may name each of the blocks you save.


Domain reputation itself

All email clients work for their users. People choose the email services they trust. We rely and account on them. Thus, email clients are supposed to protect us from emails that are sent by fishy senders.

And the first step for an email service is to make sure they transfer only legitimate emails. How can they be sure?

They judge by domain reputation. The latter depends on the complaint rate, which folder the emails are delivered to.

Spam testing

Before sending emails out, always, please always! test them with an anti-spam tool.

It will give you a  total score, will show if all the links work, etc.



By sticking to these simple rules you can protect your emails from going to spam. And by only using our editor, you can decrease your spam rate by 23%.

In order to save you some time, we tested all our email templates. Their average image-to-text ratio is 70/30.

I sincerely hope all your emails will reach their goals, get into the inbox folders. And customers will enjoy reading them.

Вячеслав Князев 2 years ago

Mail-tester уже совсем неудобный инструмент стал из-за своих ограничений. Намного удобней пользоваться

Hanna Kuznietsova commented to Вячеслав Князев 2 years ago

Вячеслав, Благодарю за комментарий и за инструмент. Я его попробовала, но мои сообщения этот сервис так и не проверил. Позже попробую еще )

John Dow Auri 3 years ago

Вот везде пишут %-е соотношение текста к изображениям. А можно пример - как это посчитать? В чем это изначально меряется? - площадь, покрытая письма картинками /длина текста в символах и длина ссылки на картинку итп

Hanna Kuznietsova commented to John Dow Auri 3 years ago

John Dow Auri, Здравствуйте. Спасибо за вопрос. Есть верный способ проверить соотношение (он описан в статье): воспользоваться услугами сервиса (данная услуга бесплатна). Проанализировав сообщение, сервис покажет в процентах, сколько текста в данном сообщении. Оптимально же, при создании сообщения, чтоб на одно изображение приходилось два небольших абзаца с текстом. Как правило, в таком письме, соотношение выдержано. И mail-tester это подтвердит. Текстом считается не только описание услуг, поздравления и т.д., но и меню, строки "отписаться" и "изменить предпочтения", строка, в которой Вы указываете причину, по которой письмо отправлено именно этому получателю, и Ваша контактная информация. Некоторые сайты полагают, что учитывается размер картинок, то бишь, спам-фильтры оценивают именно внешнее соотношение. Другие сайты полагают, что спам-фильтры оценивают код: количество символов в коде картинки/фона к количеству символов в самом тексте письма. Согласно исследованиям Email on Acid, в промо письмах должно быть более 500 знаков текста, не смотря на количество картинок. Если же текста меньше, то шансы попасть в спам равны 75%. На практике же (согласно данным некоторых ESP), как я уже писала выше, идеально, если на одно изображение приходится 2 абзаца текста. Такие письма успешно проходят спам-фильтры. Рекомендуем проверять письма в mail-tester перед отправкой. Надеюсь, я смогла ответить на Ваш вопрос. Желаю удачи в дальнейших рассылках.

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