When it comes to email design, size matters — especially if you want your message to reach the inbox fully intact. An oversized email can slow down loading times, trigger spam filters, or worse: get clipped by email clients.

In Gmail, for instance, any email larger than 102 KB will be cut off, potentially hiding your most important content or call-to-action.

So, how do you reduce email size without compromising on design? In this guide, we’ll show you how to reduce email size with 5 smart hacks you can apply right away in Mail Designer 365 – so your emails stay lean, fast, and fully visible.

5 Smart Ways to Reduce the Size of Your HTML Email

1. How to Reduce Email Size with Smarter Content

Reducing email content is the easiest and most effective way to shrink your HTML email size. Evaluate whether all the included text, images, or sections are essential.

Pro tip: Instead of cramming everything into one email, link to landing pages for more in-depth info. This keeps your email short while still providing value.

2. Reduce Email Size by Minimizing Layout Blocks

Too many layout blocks = bloated HTML. While layout blocks help organize your content, using too many separate image and text blocks will quickly bulk up your email size.

Instead, use combi layout blocks in Mail Designer 365 to place text and images side by side within the same block — this reduces code and keeps things compact.

3. Use Padding to Shrink Your Email File Size

Spacer blocks add extra HTML code to your email. To reduce file size, use the padding tool (found in the Style menu) instead.

Adjusting padding between blocks gives you the same visual spacing without the added HTML load.

Use the padding tools to reduce use of spacer blocks

4. How to Optimize Images to Reduce Email Size

Images are one of the biggest contributors to email file size. That’s why image optimization is key.

Mail Designer 365 includes built-in tools to:

• Automatically choose the optimal image format
• Compress image size and quality without losing visual impact

Use image optimization to configure the optimal size and resolution for images

Bonus Tip: Add brief and relevant alt text to each image — not only for accessibility, but also to keep your HTML lean. Mail Designer makes this easy via the “Edit Link & Background” option.

5. Replace Image Buttons to Help Reduce Email Size

Image-based buttons look nice — but they also increase your email’s size. Switch to HTML text buttons to cut file weight and improve performance across devices.

Text buttons:

• Load faster and keep your email size small
• Are fully customizable with fonts, colors, and styles
• Work better on all screen sizes and email clients

Instead of using heavy images for call-to-actions (CTAs), design sleek and modern buttons using HTML Text Buttons directly in your Mail Designer Design.

Learn how to create text buttons in Mail Designer 365

Bonus Hack: Use the Pre-Flight Checker

Want to know the size of your email before sending? Mail Designer 365’s Pre-Flight Checker shows you exactly how large your design is — so you can make edits and stay under the clipping limit.

The pre-flight checker lets you know the exact size of your design.

Final Thoughts on How to Reduce Email Size

Keeping your email design under control ensures your message gets seen in full, loads quickly, and doesn’t overwhelm your readers (or their inboxes). By following these simple tips on how to reduce email size, you’ll be designing sleeker, more efficient emails in no time.

Ready to get started? Try these tricks today in Mail Designer 365.

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