Making emails safer for all users — Stripo.email

Previously, we touched upon the importance of accessibility of online resources and the consideration of web-inclusive categories of users. However, we didn’t raise this topic offhandedly. At Stripo, we strive to make our product as user-friendly as possible, keeping our members’ well-being in mind. This is why we began exploring the topic of web inclusivity for various groups to improve and adapt our product and perhaps even help our colleagues in the industry.

Exploring the impact of photosensitive epilepsy

Today, I explore the topic of photosensitive epilepsy — what causes it, who is affected, how it impacts those who work or spend long hours at a computer, and what should be considered when designing email templates to ensure they are comfortable for both email marketers with photosensitive epilepsy and recipients who are simply email users.

Understanding the scale of the issue

Let’s dive into the issue. Worldwide, 50 million people live with epilepsy. Epilepsy is not only hereditary but can also be acquired in many cases. In simple terms, it is caused by biological or structural processes in the brain that trigger the condition, such as head injuries, strokes, infections, and even alcohol abuse.

Approximately 3% of the global population with epilepsy has photosensitive epilepsy. What does this mean? It implies that a person can experience a seizure when exposed to a flashing image, GIF, or a combination of colors. This manifests as convulsions and temporary confusion, which is similar to other forms of epileptic seizures, with slight differences in reactions.

Symptoms and effects of photosensitive seizures

What does a person feel during a seizure?

• sudden overwhelming panic;
• dizziness and numbness;
• occasionally, hallucinations.

What happens during a seizure? The person experiencing a seizure is unconscious, but their muscles tense up, and this is followed by a sudden jerking of the limbs. After the seizure, the person may experience headaches, disorientation, muscle pain, and feelings of depression.

The reach of photosensitive epilepsy in email marketing

I’ve described all this so that every person who reads this understands how difficult life can be for people with this condition. It’s crucial to ensure that nothing we create in our work even hints at triggering a seizure, let alone actually causing one.

Let’s consider the scale of the problem.

Every day, 347 billion emails are sent and received by 40 billion people around the world. If we estimate (albeit indirectly) that 50 million people have epilepsy, we can compute that these people receive approximately 433.75 million emails daily. This implies that an individual with epilepsy could receive almost nine emails per day. While this is an approximate figure, the scale is still striking.

If 3% of people with epilepsy are photosensitive, that accounts for 13.5 million emails a day being sent to individuals with this condition. Even if people with this condition receive only two emails a week, even if one of them triggers a seizure, it is highly dangerous.

Key accessibility requirements for photosensitive epileptic users

I hope you have been able to grasp the magnitude of this issue with just this one group of web-inclusive users. Let’s follow all necessary guidelines when designing emails to reduce the risk of triggering seizures to zero.

So, what accessibility requirements should we follow for this group?

Images, GIFs, and videos: The most dangerous triggers

1. Flashing images lasting more than five seconds are prohibited, as they can trigger a seizure. Avoid content with flashing frequencies between 5 Hz and 30 Hz. This frequency range is most likely to provoke seizures in people with photosensitive epilepsy. If flashing is necessary, its frequency should be less than 3 Hz or more than 60 Hz to minimize the risk of seizures.
2. More than three flashes per second (such as in a GIF) that cover 25% or more of the screen are prohibited.
3. Moving or repetitive patterns (for example, in a game) covering 25% or more of the screen are prohibited — particularly those with repetition frequencies between 5 Hz and 30 Hz.
4. Static patterns covering 40% or more of the screen are prohibited.
5. More than eight static or five moving stripes with high contrast — whether parallel, radial, curved, or straight — are prohibited. These stripes may be oriented in any direction. Moving stripes can create additional visual stimulation that increases the risk of photosensitive seizures.

Best practices for text and fonts

Text and fonts are generally less likely to trigger seizures in individuals with photosensitive epilepsy compared to environmental factors such as sunlight flickering through trees. However, remember that large text should have a contrast ratio of at least 4.5:1 for normal text and 3:1 for larger text.

Nevertheless, it’s crucial to ensure the following aspects in emails:

1. Avoid fonts with thin lines or decorative features. Sans-serif fonts (such as Arial or Helvetica) or fonts with clear, bold lines (such as Verdana) are considered more readable.
2. Avoid cursive or italic fonts in the main text, as they can reduce readability.
3. The line height should be at least 1.5 times the font size for the main text. This improves readability and reduces eye strain.
4. Paragraph spacing should also be sufficiently wide to ensure that the text is easily readable. Spacing that is at least 1.5 times the line height is recommended.

Important to note: All the rules for web-inclusive users with epilepsy can be found in the Web Accessibility Initiative Standards.

Ensuring appropriate contrast in email design

Important to note: The use of vibrant red and blue colors can trigger a seizure!

Let’s talk a bit about contrast.

1. Screen contrast is the ratio between the brightest white and the darkest black on the screen. The recommended contrast ratio is usually 1000:1 for most tasks. It’s important to avoid overly sharp transitions between bright and dark areas.
2. Color temperature: The screen color temperature is measured in Kelvins (K).

   • day mode: Usually 6500K, which corresponds to natural daylight;
   • evening or night mode: 3000K–4500K, which reduces eye strain and the risk of seizures.

3. Blue light reduction: Some programs and devices allow for the reduction of blue light intensity, which can contribute to eye strain and trigger seizures in sensitive individuals.
4. Pulse width modulation (PWM) and screen flicker: It’s important to consider technology that reduces screen flicker. Flicker at low brightness levels can be invisible to the eye but still cause discomfort and provoke seizures. Screens with flicker-free technology, for example, minimize or eliminate flicker.

Designing safer emails: Practical tips

Design and visual accessibility

1. When creating email templates, consider the contrast between text and background. Use high contrast (such as black text on a white background) to improve readability and ensure accessibility for visually impaired users.
2. Color temperature and blue light adjustment: These factors can be important for people reading emails at different times of the day. Reducing brightness and using warmer tones in the evening can help reduce eye strain.

Optimization for different devices

1. Screen brightness and flicker affect how content is perceived, so test your templates on various devices and screens to ensure the content is displayed correctly and safely for all users.

The benefits of dark mode for photosensitive epileptic users

Dark mode benefits photosensitive individuals as it reduces screen brightness, which can reduce visual strain and decrease the likelihood of triggering seizures — less light equals fewer potential seizure triggers. Dark mode can also make screen viewing less aggressive on the eyes, particularly in low-light conditions, thereby promoting overall comfort.

However, be mindful of text contrast on a dark background, as sharp white-on-black contrasts can cause visual discomfort, potentially leading to a seizure. Additionally, consider the background when developing templates, designing content, and writing email copy, particularly if your emails include animations or interactive elements.

Wrapping up

People with photosensitive epilepsy are most affected by flashing, blinking, and overly contrasting visual elements (even static ones). To avoid triggering painful and uncomfortable seizures, follow the WAI standards and provide warnings about animations, interactive content, or any epilepsy-triggering elements at the beginning of your email.

Remember, the effectiveness of your emails isn’t merely measured by raw numbers but by the comfort and safety they provide to all users.