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Mail Designer 365 Newsletter Academy

Jan 26 2026
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5 Ways to Adapt Email Designs for Apple AI Summarise

By Team equinux Mail Designer 365 Newsletter Academy, Newsletter

The Apple AI Summarise feature on macOS and iOS is changing how people consume email. For email marketers and designers, this is more than a trend or tech curiosity, it’s a clear signal that email design and copywriting need to work harder to get noticed.

Email is still a powerful marketing channel, but the rules are constantly evolving. AI email summarisation tools reward clarity, structure, and readability and penalise clutter and visual-only content. Understanding this shift is critical for email marketers.

What is Apple AI Summarise?

Apple AI Summarise is an Apple Intelligence feature that automatically condenses emails into short, digestible overviews. Instead of reading an entire message, users now just need to click – or tap on iOS – to see a brief summary highlighting the most important points:

apple AI summarise email feature in Mail

Users can click the Summarise icon to get a brief summary of the email

Why it matters for email marketing:

  • Faster reading: Users can quickly grasp your message without looking at the actual email.
  • New first impressions: The summary often becomes the primary way your email is consumed. Think subject line but with less intrigue.
  • Design impact: Poorly structured emails risk being misinterpreted or the core message downplayed.

In short, Apple AI Summarise makes your email design and copy more important than ever.

Which Other Email Clients Are Using AI Summarise?

At present, two major email clients are leading the charge when it comes to AI Summarise features:

Apple Mail

  • Offers a built-in AI Summarise feature on macOS 15.1 or later (Apple M Chips) and iOS 18.1 onwards (iPhone 15 Pro, 15 Pro Max, and iPhone 16/7).
  • Summaries appear directly in the inbox, giving recipients a quick overview.
  • Encourages glanceable email design, making hierarchy and clarity essential.

Apple AI Summarise tool in the Mail app on macOS

Gmail

  • The Gemini sidebar in Gmail uses AI to summarise emails – including long threads and complex conversations.
  • Provides condensed overviews of key points, decisions, and next steps.
  • Rewards concise and structured copy for better AI summarisation.

Gemini AI summarise tool in Gmail

Other clients, including Yahoo and Canary Mail are exploring similar features, but Apple Mail and Gmail represent the largest user base and the clearest implementation.

How Apple AI Summarise Affects Your Emails and Recipients

The AI email summary works as the new email preview. If the reader isn't drawn in by what they see there, the chances of them scrolling down to the main design are low. This means many recipients may never view the whole email.

What this means for you? The summary needs to be effective in order to accurately convey your message and convince readers to scroll down and click your CTA (call-to-action.)

How to Design Emails for AI Summarise

In order for AI summaries to be accurate and engaging to the recipient, email marketers and designers need to optimise email structure and readability.

Here are 5 useful tips on how to successfully create emails for AI:

1. Lead with the main point

Benefit-driven messaging works really well here. Try and make your “why it matters” obvious in the first paragraph so that the summary picks it up right away.

2. Use real text

Images are great to add visual flair but now it's more important than ever to use real text for everything that matters. Headlines, subheadings, and prices should all be actual text, not baked into images.

Example 1: This email promotion by character.com is image heavy, and as a result, Apple's AI Summarise isn't able to include the hero hook or any of the offer prices in its summary:

image heavy email

Image-heavy emails don't work well with Apple AI Summarise

Apple AI Summarise in action for an email campaign from character.com

Example 2: In contrast, this email from Thornton's uses real text for the main part of the email - including the offer code. Because of this, the Apple AI Summarise was able to include the code directly in the summary, giving recipients an extra opportunity to redeem even if they don't scroll all the way down.

Apple AI Summarise for a free delivery email promotion by Thorntons

This summary works much better due to the use of real text in the design

3. Opt for text buttons instead of images

On a similar note, it's also advisable to use text buttons for your email's CTAs. This has always been a best practice to avoid rendering issues but now also helps ensure that AI can include your core call-to-action in its summary.

To add a text button in Mail Designer 365, simply highlight your chosen text and go to Insert > Text Button in the app menu. You can then choose from a wide range of pre-defined styles or create your own:

add stylised text buttons for easier interpretation by Apple AI Summarise

Apple AI Summarise can interpret text buttons much easier than images

 

4. Establish hierarchy with text styles

Use headings, subheadings, and body text consistently to guide readers and AI summarisation on the most important aspects of your campaign.

Mail Designer 365 supports default text styles for all email designs: new layout blocks will automatically be assigned headline or body text which ensures consistency and a clear hierarchy within your email.

5. Include alt text

This is not only an accessibility best practice, but also important for AI summarisation. If you are using images in your design, including an alt text is a way to tell the AI technology exactly what the image shows, whether it's a special offer, new product or important news. Forgoing the alt text means important visual elements of your newsletter may not be included in the summary.

 

Optimise Your Emails for Apple AI Summarise with Mail Designer

AI summarise in clients like Apple Mail and Gmail isn’t a threat. In fact, it’s a useful signal to focus on clarity, hierarchy, and readability even more than before. Emails that are structured, concise, and scannable perform better for both AI and human readers.

Looking for a design tool for AI friendly emails? Mail Designer makes it easy to include best practices for AI in your email designs without compromising on style or branding.

Try Mail Designer 365 for free

Design and send emails without code – 7 days free on your Mac.

Try for free

Compatible with macOS 10.13 or later
Jan 26 2026
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email design for dark mode: choosing a color scheme

Email Design for Dark Mode – Best Practices for 2026

By Team equinux Mail Designer 365 Newsletter Academy

Email design for dark mode can seem like a jungle. With macOS, iOS, and many popular email clients now supporting system-wide dark mode, your newsletters can appear differently depending on your recipient’s settings.

In this guide, we’ll explore how to design emails that look great in dark mode, avoid common pitfalls, and use Mail Designer 365 to create emails that stay consistent across clients.

How Dark Mode Works in Email Clients

Unfortunately, there's no universal way that email clients deal with dark mode, but knowing the behavior of each client helps you anticipate how your design will render.

At the time of writing, the most popular email clients handle dark mode in the following ways:

Client Typical Dark Mode Behavior Notes
Apple Mail (macOS & iOS) Partial or no color change; supports CSS overrides Backgrounds and text may invert depending on images and HTML/CSS
Gmail (Web/Desktop) No color change Email appears the same regardless of dark UI mode
Gmail (Mobile) Partial or full color inversion Backgrounds and text can be inverted; limited support for CSS overrides
Outlook (Windows Desktop) Often full color inversion Backgrounds and text can invert; images mostly preserved
Outlook (Web/Mac/Mobile) Partial inversion Backgrounds and text may invert; behavior varies by platform
Yahoo Mail Full inversion Light backgrounds become dark, text colors change accordingly
AOL / Legacy Clients No change Email appears the same as in light mode

Email Design for Dark Mode: Common Issues

Text color and readability changes

When emails are displayed in dark mode, text colors can invert or shift automatically, which may reduce contrast and make your message harder to read. Light text on light backgrounds or dark text on dark backgrounds can appear unintentionally.

Image inversion or unexpected transparency

Some email clients invert colors in images or treat transparent areas differently, which can distort logos or design elements. Images with white or light-colored backgrounds may appear dark, and partially transparent graphics can render inconsistently.

Background colors appearing darker or lighter than intended

Background colors can shift unexpectedly in dark mode, sometimes making sections too dark or washing out lighter colors. This affects overall layout and the visual balance of your email.

Call-to-action buttons losing contrast

Buttons and other interactive elements may lose contrast when colors invert, reducing click-through rates. Dark text on a dark button or light text on a light button can become unreadable.

Best Practices for Dark Mode-Compatible Emails

If you're wondering how best to handle email design for dark mode, these best-practice tips provide a good basis:

Use universally-acceptable color palettes

When colors are inverted, it can lead to rendering issues in dark mode. For this reason, it's advisable to choose colors that work in both light and dark modes to maintain readability and brand consistency.

Not all high-contrast combinations are safe. For example, pure black (#000000) text on a pure white (#FFFFFF) background, or the reverse, can create harsh visual contrast that strains the eyes and may invert unpredictably in some email clients. Instead, use slightly softer tones, such as dark gray (#111111) on off-white (#F9F9F9), or near-white (#FAFAFA) on very dark gray (#111111). These combinations maintain readability, look pleasant on all devices, and invert more gracefully in dark mode.

email design for dark mode: choosing a color scheme

Do:

  • Use dark gray shades instead of pure black for text
  • Use off-white or very light gray instead of pure white for backgrounds
  • Test your color combinations in multiple clients to ensure readability in both light and dark modes

Don’t:

  • Avoid pure black on pure white or vice versa
  • Avoid pastel colors on light backgrounds; they often lose contrast in dark mode
  • Avoid bright neon or highly saturated colors that can invert unpredictably and reduce legibility

Keep branding simple

Avoid overly complex gradients, textures, or background patterns that invert poorly; simple designs translate better across clients.

Alt text for images

As well as being important for accessibility, alt text also works as an additional security net for ensuring your email renders effectively. Adding descriptive alt text means your message remains understandable even if images are altered or blocked in dark mode. For example:

  • Icons for buttons – e.g., a dark “download” icon on a light button. If colors invert, the icon may vanish or be unclear
  • Product images on light backgrounds. The product might get lost against a darkened background in dark mode
  • Decorative or infographic images that convey information by color or shape; inversion can make them misleading

Use Mail Designer's alt text interface to easily add descriptive alt text for your newsletter images and ensure compatibility for dark mode.

alt text editor in mail designer 365 helps when negotiating email design for dark mode

Include a "View in browser" link

Provide a fallback so recipients can see your design as intended if dark mode alters the email. This is the ultimate backup plan for your emails, especially if you aren't sure which email clients your recipients are using.

view in browser link in an email

Including a view in browser link is a good backup plan for dark mode

To add a view in browser link to your template, check out this HTML export guide.

Test across clients and devices

Mail designer 365 Testmail is a great dress rehearsal before sending out the real campaign to your audience so you can preview how your email renders in real inboxes on desktop and mobile before sending. More about Testmail →

Testmail service in Mail Designer 365

Send a test version of your email via the Mail Designer 365 Testmail service

You can also preview your emails in multiple clients using tools like Litmus or Email on Acid to catch dark mode issues before sending.

Dark Mode Tips for Specific Email Clients

If you know a large segment of your audience is using a particular email client, you can use client-specific tweaks and testing methods to ensure widespread compatibility.

  • Apple Mail: Light and dark versions may auto-switch; test plain-text sections separately.
  • Outlook: Avoid dark mode auto-inversion issues by using consistent background colors and avoiding semi-transparent images.
  • Gmail: Test for dark mode on web and mobile; inline CSS helps maintain colors.
  • Others (Yahoo, ProtonMail, etc.): Keep designs simple; fallback colors ensure readability.

Email Design for Dark Mode: Quick Checklist

  • ✅ Use high-contrast color palettes that work in both light and dark modes
  • ✅ Avoid pure black on white (and vice versa); use soft gray tones instead
  • ✅ Keep branding simple; avoid complex gradients or patterns that invert poorly
  • ✅ Add descriptive alt text for all images, icons, and critical visual elements
  • ✅ Include a visible “View in browser” link as a fallback
  • ✅ Test your email in multiple clients and devices using Testmail, Litmus, or Email on Acid

Email design for dark mode is now a daily consideration for email designers. By using Mail Designer 365 features, following high-contrast design rules, and testing across clients, your newsletters can look polished and professional no matter what mode your readers are using.

Try Mail Designer 365 for free

Design dark mode friendly emails without code – 7 days free on your Mac.

Try for free

Compatible with macOS 10.13 or later
Jan 19 2026
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inserting the email placeholder into the link field to pre-fill email address in a url

How to Pre-Fill Email Address in a URL for Better Email Campaigns

By Team equinux Mail Designer 365 Newsletter Academy

Pre-filling an email address in a URL is a simple but powerful technique for improving user experience and increasing conversions. In this guide, we’ll show you how to include the email parameter in a URL, and how to pass email placeholders from your email builder for highly-personalised email campaigns.

What Does It Mean to Pre-Fill Email Address in a URL?

Pre-filling an email address means automatically inserting an email into a form field when they land on a page. This is usually done by adding a query parameter to a URL, such as ?email=example@email.com.

When the page loads, the form reads this parameter and populates the email field for the user, removing friction and saving time.

Why Pre-Filled Email Links Increase Conversions

1. Fewer Steps for the User

Every additional field a user has to type is a chance for them to abandon the page. Pre-filling an email address removes one small but meaningful hurdle.

2. Better Experience on Mobile

Typing on mobile devices is slower and more error-prone. Automatically inserting the email address makes sign-ups and requests much smoother on smaller screens.

3. Higher Accuracy, Fewer Typos

Passing the email address directly from your email campaign ensures the address is entered exactly as intended, avoiding misspellings or formatting issues.

4. Ideal for Sign-Up Pages and Lead Forms

This technique works especially well when linking from newsletters, onboarding emails, webinar invitations, or gated content pages where the user is already known.

Suggestion: Building signup forms in Mail Designer 365 →

Common Use Cases for Pre-Filled Email URLs

  • Newsletter sign-up pages
  • Webinar or event registration forms
  • Free trial or demo request pages
  • Account activation or onboarding flows
  • Feedback and survey form

How the ?email= URL Parameter Works

At its simplest, a pre-filled email URL looks like this:
https://www.example.com/signup?email=example@email.com
The email parameter is read by the landing page and mapped to the email input field. Most modern form builders and marketing tools support this behavior out of the box.

So far, so good.

However, when sending campaigns to large groups, you won't be able to manually personalise each link. Instead, you need a placeholder that gets replaced for each recipient when you hit send.

Using Email Placeholders in Your Email Campaigns

Email placeholders allow you to dynamically insert recipient data, such as email addresses, into links. When the campaign is sent, each recipient receives a personalized URL.

The exact placeholder syntax depends on your email builder. In Mail Designer 365, placeholders are handled directly inside the editor and automatically populated during sending.

Step-by-Step Guide: Pre-Filling Email Addresses with Mail Designer 365

Here is a step-by-step walkthrough showing how to insert an email placeholder into a URL using Mail Designer 365. This ensures each recipient’s email address is passed correctly to your landing page.

We will use one of our recent campaigns as an example.

  1. Enter the main part of your landing page URL, including the email parameter, for example: https://maildesigner365.com/free-mail-designer-365-consultation?email= URL with email parameter before inserting the placeholder
  2. Right click after the = symbol and select Insert Placeholder > Mail Designer Standard Placeholders Inserting an email placeholder to pre-fill an email address in a URL
  3. Select Email from the list. The placeholder will now appear in the link field. Email placeholder inserted into the URL field
  4. When you send your email, the placeholder is automatically replaced with the recipient’s email address. The form on your landing page will already be filled in, so the user only needs to click once. Result: email address pre-filled in the sign-up form from the URL
P.S. Want to send personalised emails to your audience? Check out this guide to sending in Mail Designer 365.
Remembering to pre-fill email addresses in URLs is a small technical tweak that can bring big benefits. When combined with personalized email campaigns from Mail Designer 365, it helps create smoother journeys, higher conversions, and happier recipients.

Try Mail Designer 365 for free

Design and send emails without code – 7 days free on your Mac.

Try for free

Compatible with macOS 10.13 or later
Jan 13 2026
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SMTP alternative: Mail Designer 365 Direct Mail interface for sending professional HTML emails directly from your Mac.

Microsoft 365 SMTP Not Working? Try This Instead

By Team equinux Mail Designer 365 Newsletter Academy, Newsletter Academy

Switching your email account to Microsoft 365 can sometimes cause unexpected issues, especially when sending emails via SMTP through third-party apps like Mail Designer 365. Many users report that after the migration, their newsletters or other outgoing emails fail to send, even though login credentials remain correct. This article explains why this happens and provides you with a straightforward fix to help get you back on track.

Why Microsoft 365 SMTP Access May Fail

Many Microsoft 365 plans no longer provide traditional SMTP access in the way third-party apps expect. In some cases, SMTP is completely blocked, or it requires complex OAuth2 authentication. The classic login method, using just a username and password for SMTP, IMAP, or POP3, is often disabled by default after migration. This means that even if your app password is correct, third-party apps may fail to authenticate with Microsoft’s servers.

How This Affects SMTP Sending in Mail Designer 365

Mail Designer 365's SMTP send feature relies on a working SMTP connection to send emails. If your SMTP connection is blocked or requires a protocol the app doesn’t support, the login to the mail server will fail, and sending emails will not work. Users often encounter error messages indicating authentication failures, which can be confusing if email credentials work in other apps like Apple Mail or Outlook.

An Alternative to SMTP in Mail Designer

If SMTP sending is no longer available with your Microsoft 365 account, Mail Designer 365 offers a built-in sending service that avoids these limitations altogether.

Mail Designer 365 provides two integrated sending options:

  • Direct Send – ideal for 1:1 emails and smaller recipient groups, similar to traditional SMTP sending
  • Campaign Sending – designed for marketing newsletters and larger email distributions

Both options allow you to send emails without relying on your email provider’s SMTP access, making sending more reliable and easier to maintain as provider requirements continue to change.

SMTP alternative: Mail Designer 365 Direct Mail interface for sending professional HTML emails directly from your Mac.

With Mail Designer 365 Direct Mail, you can send professional HTML emails directly from your Mac without relying on SMTP

Good to know: All Mail Designer 365 design plans include a base sending allowance, so you can get started right away and send up to 20 Direct Mails a month, at no additional cost.

Why Use Mail Designer 365’s Sending Service?

  • Custom domain authentication: Support for DKIM, SPF, and DMARC helps ensure your emails are properly authenticated and trusted by receiving servers.
  • Improved deliverability: Modern sending infrastructure helps your emails reach inboxes rather than spam folders.
  • Less dependency on email providers: You’re no longer affected by changes to Microsoft 365 or other providers’ SMTP and authentication policies.

Alternative to SMTP: DKIM, SPF and DMARC verification ensures secure sending from your domain

By using Mail Designer 365’s sending service, you can continue sending professional emails and newsletters with confidence, even as email platforms evolve and restrict traditional SMTP access.

Helpful Resources for Sending with Mail Designer 365

Try Mail Designer 365 Sending for free

Design emails without code – 7 days free on your Mac.

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Compatible with macOS 10.13 or later
Dec 17 2025
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Best 2026 Email Ideas - Key Dates and Events for Marketers

By Team equinux Mail Designer 365 Newsletter Academy

Looking for 2026 email ideas? Planning campaigns around key dates helps your business stay relevant, engage your audience, and increase conversions throughout the year. To make your 2026 email strategy easier, we’ve compiled 12 must-know marketing dates, including holidays, global celebrations, and unique pop culture events that can inspire creative campaigns.

2026 Email Ideas You Need in Your Email Marketing Calendar

January 11 – International Thank You Day

Start the year by showing your appreciation to customers. Whether it’s a thank-you email, a loyalty reward, or a special offer, this day is perfect for building goodwill and strengthening relationships early in the year.

thank you email template

Mail Designer 365 Thank You Offer Email Template

February 17 – Lunar New Year (Year of the Fire Horse)

The Lunar New Year is celebrated across Asia and globally, making it a fantastic opportunity to send culturally relevant greetings or promotions. Bright visuals and festive messaging can help your campaigns stand out and resonate with diverse audiences.

Lunar New Year 2026 email template

Mail Designer 365 email template for Lunar New Year

March 28 – Earth Hour

Earth Hour is a global movement for sustainability, encouraging everyone to switch off lights for an hour. Align your brand with eco-friendly initiatives, share tips for reducing energy use, or highlight your company’s sustainability efforts in your emails.

April 23 – Record Store Day

Although not an obvious choice for 2026 email ideas, music fans all around the world celebrate Record Store Day. This makes it a great opportunity for campaigns centered on culture, creativity, or limited-edition product releases. Promote exclusive offers, playlists, or behind-the-scenes content to engage your audience.

vinyl record player. world record day as a 2026 email idea

World Record Store Day is a fun and quirky campaign idea for music lovers

May 4 – Star Wars Day (“May the Fourth”)

Leverage this fun pop culture moment for playful and engaging campaigns. Email content could include themed promotions, interactive quizzes, or social media tie-ins. It’s a simple way to connect with fans and inject some humor into your marketing.

June 1 – LGBT Pride Month Begins

Pride Month celebrates diversity, inclusion, and equality. Showcase your support with campaigns highlighting LGBTQ+ initiatives, employee stories, or curated product collections. Authenticity is key, so make sure your messaging is inclusive and meaningful.

LGBTQ Pride Party email template

LGBT Pride Event Template in Mail Designer

July 17 – World Emoji Day  😉🫶🐴🥑🏄🏻‍♂️🆒

Emojis are a universal language in digital communication. Use World Emoji Day to create fun, lighthearted campaigns with creative visuals, playful copy, and interactive content to boost engagement and click-throughs.

August 26 – Women’s Equality Day

Recognize the achievements and rights of women on Women’s Equality Day. This is a perfect addition to your 2026 email ideas list. Highlight women leaders in your company, promote initiatives for gender equality, or run campaigns that empower your audience.

2026 email ideas: email template for women's equality day

Mail Designer 365 Email Template for Women's Equality Day

September 19 – Oktoberfest Begins

Prost! 🍻 The world’s largest beer festival kicks off in Munich, Germany. Embrace Oktoberfest themes for promotions, events, or themed product launches. Highlight community, fun, and celebration to engage audiences during this festive period.

October 10 – World Mental Health Day

Promote wellbeing and support your community by raising awareness around mental health. Share tips, resources, or charitable campaigns in your emails. Showing genuine care can build trust and resonate with your audience.

November 11 – Singles’ Day

Originating in China, Singles’ Day has grown into one of the biggest shopping days in the world. As 2026 email ideas go, this one is a must-have for any marketer. Offer exclusive deals, flash sales, or gift guides to capitalize on this massive e-commerce opportunity.

Singles Day sales email idea for 2026

Singles Day is just one day. Make this clear in your campaign to help generate a sense of urgency.

December 6 – St Nicholas Day

Mark the start of the festive season in Europe with early holiday campaigns. Previews, special offers, or themed storytelling can help you warm up your audience ahead of Christmas promotions.

Celebrate St. Nicholas Day in the run up to Christmas.

Planning Ahead for 2026

These are just 12 email ideas for 2026 and provide a framework for creative, timely email campaigns that keep your audience engaged all year. Plan your visuals, copy, and offers around these events to make 2026 your most successful marketing year yet.

Hungry for more design inspiration? Check out all our Design Ideas for seasonal, sales, events and more!

Try Mail Designer 365 for free

Design emails without code – 7 days free on your Mac.

Try for free

Compatible with macOS 10.13 or later
Sep 22 2025
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DKIM Setup: How to Verify Your Email Domain Easily

By Team equinux Mail Designer 365 Newsletter Academy

With Google's latest announcement that DKIM is becoming mandatory for mass email senders from 2024 onwards, many email marketers are wondering how to prepare.

The good news: DKIM setup does not have to be complicated. This guide walks you through DKIM setup for your email domain so you can improve deliverability and continue sending authentic, spam compliant email campaigns in the new year and beyond.

Read More

Sep 11 2025
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Side-by-side comparison of the same HTML email sent with Thunderbird (left) and Mail Designer 365 (right), showing layout and rendering differences.

HTML Email Thunderbird: 3 Limitations & Better Options

By Team equinux Mail Designer 365 Newsletter Academy, Newsletter Academy

Thunderbird is a popular free email client used by individuals and small businesses around the world. One of the most common questions users ask is whether it’s possible to create and send an HTML email Thunderbird. The short answer is yes — Thunderbird does allow you to use HTML templates. However, once you start designing and sending more professional messages, you’ll quickly run into limitations that make the process frustrating and time-consuming.

Can You Create HTML Email in Thunderbird?

Yes — Thunderbird does support HTML emails. You can import a custom template or even write your own code directly inside the editor. For users who just want to test a simple HTML email Thunderbird workflow, this can work fine. At first glance, it looks like Thunderbird could handle newsletters or business updates by using HTML templates. If you want to try it out yourself, follow our step-by-step guide on how to export HTML emails from Mail Designer 365.

hunderbird Insert menu showing the HTML option for composing emails

In Thunderbird, you can choose the HTML option from the Insert menu to add custom code to your email.

HTML Email Thunderbird Insert HTML window for adding custom HTML email code

Thunderbird allows you to paste custom HTML code into your message — but editing and formatting remain limited.

The Limitations of HTML Email Thunderbird

While you can technically create and send HTML email Thunderbird, the process comes with serious drawbacks:
  • Editing issues: Imported designs display distracting red lines, which makes it difficult to edit the template.
  • Image problems: All images need to be reconnected manually, adding unnecessary extra work.
  • Layout limitations: Backgrounds don’t extend to the full width of the email. Instead, white gaps appear at the top, left, and bottom, making your message look unfinished.
  • Attachments or hosting: Every HTML email Thunderbird sends must either include attached images (making emails heavier) or rely on external hosting.
These issues mean that while Thunderbird is capable of sending HTML emails, it’s not well-suited for creating professional designs that need to look polished across different devices and email clients.

Why These Issues Matter for Your Business Emails

When sending out business communications, appearance and reliability matter. Using HTML email in Thunderbird may work for simple messages, but the limitations can cause real problems:

  • Unprofessional look: Broken layouts, misaligned backgrounds, and missing images make your brand appear less trustworthy.
  • Wasted time: Fixing every HTML email Thunderbird sends is inefficient.
  • Inconsistent results: Emails that don’t render properly across devices risk confusing or frustrating your audience.
  • Heavier emails: Thunderbird requires you to either attach all images to the message (making the email larger and more likely to hit spam filters) or host them externally, adding another layer of complexity.
  • No performance insights: Without tracking, you can’t see who opened your email or what links they clicked.
For personal use, these issues might be minor annoyances. But for businesses, they can directly affect engagement, credibility, and results.
Side-by-side comparison of the same HTML email sent with Thunderbird (left) and Mail Designer 365 (right), showing layout and rendering differences.

The same HTML email sent with Thunderbird (left) shows formatting issues and requires image attachments, while Mail Designer 365 (right) delivers a clean, professional result.

A Better Alternative to Thunderbird HTML Email

If you want professional results without the frustration, Mail Designer 365 offers a smarter solution. Instead of struggling with the limitations of HTML email Thunderbird, you can use Mail Designer’s built-in Direct Mail function to design and send polished emails directly from your Mac.
With Mail Designer Direct Mail, you can:
  • Design with ease: Drag-and-drop tools make it simple to create professional layouts without code.
  • Send without issues: Emails go out exactly as designed, without red lines, broken images, or layout gaps.
  • Use your contacts: Send messages directly to people in your Mac address book.
  • Keep a record: BCC yourself automatically to track what was sent.
  • Measure performance: Built-in tracking shows who opened your email and what they clicked.
This means less time fixing errors and more time focusing on creating impactful, engaging content for your audience. Learn more about how to get started with Mail Designer Direct Mail and send professional emails without the limitations of Thunderbird.
Mail Designer 365 Direct Mail interface for sending professional HTML emails directly from your Mac.

With Mail Designer 365 Direct Mail, you can send professional HTML emails directly from your Mac — without broken layouts, missing images, or large attachments.

Conclusion

Creating and sending HTML email Thunderbird is technically possible, but the experience is far from smooth. From broken layouts to constant image reconnecting, Thunderbird’s limitations make it difficult to achieve a professional result.

If your goal is to send emails that look polished, work reliably across devices, and provide insights into performance, Thunderbird will quickly feel restrictive.

That’s where Mail Designer 365 comes in. With powerful design tools and the integrated Direct Mail function, you can create beautiful HTML emails and send them directly — without the headaches.

Try Mail Designer 365 today and experience a better way to design and send professional emails.

 

Try Mail Designer 365 free for 7 days

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