Guideline

Why

Keep it under 50 characters

Longer subject lines get cut off on mobile. Aim for 40–50 characters to ensure the full message is visible.

Lead with the value

Put the most important word or benefit first. Recipients scan left to right and decide in under 2 seconds.

Be specific, not vague

"3 tips for better email open rates" outperforms "Our latest newsletter" every time. Tell the reader what's inside.

Create relevance, not just urgency

Urgency works occasionally ("Ends tonight"), but overuse trains recipients to ignore it. Relevance ("Based on your recent purchase") is more sustainable.

Avoid common spam triggers

Words like "FREE", "WINNER", "ACT NOW", all-caps text, and excessive punctuation (!!!) can trigger spam filters or make your email look untrustworthy.

Use personalisation wisely

Including the recipient's name or location can boost open rates — but only if the data is clean. A subject line that says "Hi ##firstname##" because the Attribute is empty does more harm than good.

Guideline

Why

Use a recognisable sender name

Use your brand name or a combination like "Anna at [Brand]". Avoid generic names like "Marketing" or "noreply".

Use a real, monitored reply-to address

Recipients sometimes reply to marketing emails. A monitored reply-to address shows you're listening.

Be consistent across sends

Changing your sender name frequently confuses recipients and can hurt open rates. Save your sender details in a Template so they're pre-filled every time.

Send from a DKIM-authenticated domain

If your sending domain isn't authenticated with DKIM, your emails are likely to land in spam. Read more about DKIM setup

Guideline

How to apply it

One email, one primary goal

Each email should have a single, clear purpose. If you need to cover multiple topics, consider splitting into a series rather than cramming everything into one send.

Use the inverted pyramid

Lead with a compelling headline, follow with supporting text, and end with a clear CTA. Guide the reader's eye downward to the action you want them to take.

Keep modules short and focused

Break content into distinct Rows with clear visual separation. Each Row should address one idea, one product, or one message.

Use Heading and Paragraph elements correctly

Use the Heading element for headings and the Paragraph element for body text. This isn't just visual — screen readers use these to navigate the content structure.

Leave breathing room

Don't pack content edge-to-edge. Padding and white space make emails feel less cluttered and easier to scan — especially on mobile.

Guideline

Details

Use web-based fonts from the editor

The fonts available in the Inline text editor are supported across major email clients. Using unsupported fonts means email clients will substitute a fallback — which may break your design.

Body text: 14–16px

14px is ideal for longer emails. For short, punchy messages (2–3 sentences), 16px gives more impact. Go smaller than 14px only for fine print or legal disclaimers.

Headings: 20–28px

Make headings clearly distinct from body text. A heading that's only 2px larger than the body doesn't create the hierarchy you need.

Line height and spacing

A line height of 1.4–1.6× the font size improves readability. Paragraphs should have visible spacing between them.

Contrast

Ensure strong contrast between text colour and background. Dark text on a light background is the safest combination for readability.

Guideline

Details

Always add alt text

Alt text describes the image for screen readers and displays when images don't load. Make it descriptive — "Woman holding a coffee cup in a sunlit café" is useful; "image1.jpg" is not.

Make images clickable

Add a link to every image, especially your logo and hero images. On mobile, it's often easier to tap an image than to find a small text link.

Keep file sizes under 1 MB per image

Large images slow down loading — especially on mobile connections. Compress images before uploading. The total email size should stay manageable for all devices.

Use high-quality images

Avoid pixelated or low-resolution images. They undermine your brand and make your email look unprofessional.

Design for image-off scenarios

Some email clients block images by default. Your email should still make sense and be actionable without images — use background colours, alt text, and HTML text (not text-as-image) to ensure this.

Match images to your design

Select images that pair well with the surrounding colours. For example, an image with a circular shape on a black background can blend seamlessly if you set the Row background to match.

Guideline

Details

Use action-oriented button text

"Download the guide", "Book your seat", "See the collection" — tell the reader exactly what happens when they click. Avoid vague labels like "Click here" or "Read more".

Add screen reader labels

The screen reader label on a button or link describes the action in context — for example, "Opens the September product catalogue in a new tab". This is essential for accessibility.

Make buttons large enough to tap

On mobile, small buttons are hard to hit. A minimum button height of 44px is a good rule of thumb.

Place your primary CTA above the fold

The most important action should be visible without scrolling. Repeat it at the bottom for longer emails.

Limit the number of links

Too many links dilute attention. Focus on one primary CTA per email section. If you need multiple links (e.g. in a newsletter), give each one its own clearly separated Row.

Make the unsubscribe link visible

A clear, easy-to-find unsubscribe link isn't just a legal requirement — it builds trust and reduces spam complaints. Hiding it drives recipients to mark your email as spam instead, which damages your sender reputation.

Technique

When to use it

Where to learn more

Data tags

Insert Profile data (name, city, product interest) into subject lines, preheaders, and email body text. Works best when your data is clean and complete.

Data tags and Segments

Row Segmentation

Show different content blocks to different Segments within a single email. Great for tailoring offers by customer type, location, or interest — without creating multiple emails.

Data tags and Segments

Audience segmentation at send time

Filter your send audience by Segment, Tag, or Import in the Send To step. Send the right message to the right group.

Email: Create and Send

Dynamic Assets

Automatically pull in personalised product recommendations, latest blog posts, or other content from external feeds.

Creating Dynamic Assets

Guideline

How to apply it

Short subject lines

Mobile inboxes show fewer characters. Keep subject lines under 40 characters for mobile, or front-load the key message.

Concise copy

Mobile readers scan — they don't read. Lead with the point, keep paragraphs short (2–3 sentences max), and cut anything that doesn't directly support the email's goal.

Tappable buttons and links

Make buttons at least 44px tall with padding around them. Avoid placing two links side by side where they're easy to mistap.

Single-column layout for key content

Multi-column layouts can work on desktop but often stack awkwardly on mobile. Use single-column for your primary message and CTA. More about column stacking here: Email: Rows and Columns | Apsis Knowledge base

Clickable images

On mobile, it's easier to tap an image than to find a small text link. Link your images to the same destination as your CTA.

Always preview on mobile

Use the Preview → Mobile view in the editor to check how your email looks on a smaller screen before sending.

Guideline

Details

Avoid transparent PNG logos on white

In dark mode, a transparent background becomes dark — and a white logo on a transparent background disappears. Use a logo with a solid background, or add padding around it with a defined background colour.

Test your colour choices

Colours that look great on a white background may lose contrast on a dark background. Test with Litmus or other email rendering tools if possible, or at minimum, send yourself a test and check in dark mode.

Use solid background colours on images

If you use images with transparent backgrounds, the dark mode inversion may produce unexpected results. Solid backgrounds are safer.

Guideline

How to apply it

Logo at the top

Your logo or brand name should always be the first visual element. Link it to your website.

Consistent colour palette

Use your brand colours for headers, footers, buttons, and accents. This simplifies design decisions and ensures every email feels on-brand.

Save your brand elements as Assets

Create your header, footer, and common content blocks once, save them as Assets, and reuse them in every email. This guarantees consistency and saves time.

Use Templates

Save your finished email layout as a Template. Next time, start from the Template instead of a blank canvas — your brand structure, colours, and sender details are already in place.

Set up a Custom Domain

Replace the default link domain with your own branded domain so recipients see your domain when hovering over links and on system pages (web version, unsubscribe). This builds trust and reinforces your brand. Read more

Practice

What to do

Where in the editor

Semantic structure

Use the Heading element for headings and Paragraph element for body text. Screen readers use these to navigate content hierarchy.

Design Panel → Elements

Alt text on all images

Describe the image content meaningfully. If the image is decorative only, use an empty alt text rather than omitting it.

Image element → Settings

Screen reader labels on links and buttons

Add a label that describes what happens when the link is clicked — e.g. "Opens the event registration page".

Button / Link element → Settings

Set the email language

Select the language of your content so screen readers pronounce text correctly.

Settings tab → Email tab

Sufficient colour contrast

Text should have strong contrast against its background. Avoid light grey text on white, or coloured text on a busy background.

Colour settings on any element

Don't rely on colour alone

If you use colour to convey meaning (e.g. red for "urgent"), add a text label too — some recipients can't distinguish colours.

Content/copy decisions

Readable font sizes

Minimum 14px for body text. Avoid very small font sizes for anything other than legal disclaimers.

Inline text editor

Guideline

Details

Send when your audience is active

There's no universal "best time". B2B audiences often engage mid-morning on weekdays; B2C audiences may respond better on evenings or weekends. Test different times and check your reports.

Be consistent with frequency

If you promise a weekly newsletter, send weekly. Irregular frequency confuses recipients and can increase unsubscribes.

Don't over-send

Sending too frequently is one of the top reasons people unsubscribe. Use the Frequency setting in the Send To step to exclude Profiles who received an email recently.

Check the Calendar

Use the Calendar in Apsis One to see what other sends are planned. Avoid stacking multiple sends to the same audience on the same day.

Respect time zones

Scheduled sends follow the time zone set in your User Profile settings. If your audience is in a different time zone, adjust accordingly.

Factor

What to do

Authenticate your domain

Set up DKIM through your Account Manager and the Apsis Delivery team. Without DKIM, Gmail, Yahoo, and Outlook are far more likely to flag your emails as spam. Read more

Keep your list clean

Regularly review bounce rates and remove Profiles with repeated hard bounces. Apsis One automatically stops sending after 3 hard bounces per Profile, but keeping your list tidy prevents damage to your sender reputation.

Only send to consented Profiles

Never import purchased lists or send to Profiles who haven't opted in. This leads to high spam complaints, blacklisting, and GDPR violations.

Monitor spam complaints

Check your Email Report after every send. A spam complaint rate above 0.1% is a warning sign that your content, frequency, or list quality needs attention.

Warm up new domains

If you're sending from a brand new domain or private technical sender domain, start with small volumes and gradually increase over 5–7 days. Sudden large sends from a new domain trigger spam filters. Read more about warm-up

Balance images and text

Emails that are mostly images with very little text can trigger spam filters. Use a healthy mix of HTML text and images.

Check

What to verify

Sender details

Sender name, sender email, and reply-to address are correct and consistent with your brand.

Subject line and preheader

Clear, compelling, and within recommended character limits. No broken Data tags.

Content and copy

No placeholder text, no typos, all Data tags rendering correctly.

Links

All links point to the correct URLs. Test every link in your test email.

Images

All images load, have alt text, and are linked where appropriate.

Unsubscribe link

Present, visible, and working.

Mobile preview

Checked in the editor's Preview → Mobile view. Layout, text, and buttons look correct.

Test email sent

Sent a test to yourself (and ideally a colleague). Opened it on both desktop and mobile.

Audience

Correct Subscription selected. Segments and Frequency settings applied. Recipient count calculated and reviewed.

Schedule

Date, time, and time zone are correct. If split send: batches configured as intended.