Inline vs Embedded Images in Email Signatures: What’s the Difference and Why It Matters

Amy Lockwood
Amy Lockwood
Co-Founder & Head of App and Web Design (15+ Years Experience)
Updated On: Apr 25, 2025
Email Signature Support

Not all email images are created equal, especially when it comes to your HTML signature. If you’ve ever opened an email only to see a broken image icon where someone’s logo should be, you’ve experienced firsthand what happens when image handling goes wrong.

Inline vs Embedded Images in Email Signatures: What’s the Difference and Why It Matters

<img src="https://imagedelivery.net/1cNcsRZEwSQRSjEbRxir3Q/4cf495a6-2f38-4183-16f2-dc24e60cbd00/medium">

The root of the issue? Whether the image was embedded or linked inline.

Both methods work, kind of. But they behave very differently depending on your email client, device, and even the recipient's settings. Understanding the difference can save your brand from broken logos, spam flags, or inbox bloat.

Here’s a breakdown of the two methods, when to use each (or not), and how to build a signature that actually displays as intended.

What Is an Embedded Image?

Embedded images are attached directly to the email itself, like a file attachment, but hidden inside the HTML. When the recipient opens the email, the image loads from within the message, not from a remote server.

How it works:
A Content-ID (CID) is used to reference the image in the HTML code:

<img src="cid:logo123">

Pros:

  • Doesn’t rely on internet access to load
  • Sometimes bypasses external image blocking (but not always)

Cons:

  • Increases email size significantly, especially if used in every reply/forward
  • Often flagged by spam filters or antivirus tools
  • Doesn’t always render consistently across all email clients (notably Gmail)
  • Can leave image "ghosts" when replying or forwarding emails

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What Is an Inline (Hosted) Image?

Inline images are hosted on a web server and referenced by a direct URL in your HTML. They load from the internet when the email is opened.

<img src="https://yourdomain.com/images/logo.png" alt="Company Logo">

Pros:

  • Keeps the email file size small
  • Works more reliably across devices and platforms
  • Easy to update centrally (if the image changes, you don’t need to update the HTML)

Cons:

  • Requires a secure (HTTPS) image host
  • Some email clients block remote images by default until the user clicks “Display images”
  • Can break if the image is deleted or the host is down

Which Method Should You Use?

Unless you have to support offline-only environments, inline/hosted images are the clear winner for professional email signatures.

Feature Inline (Hosted) Embedded (CID)
Consistency in Gmail ✅ ❌
Small email size ✅ ❌
Easy to update image later ✅ ❌
Avoids spam triggers ✅ ❌
Guaranteed image visibility ❌ ✅ sometimes

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Common Mistake: Copy-Pasting From Word or Gmail

This is where most broken images in email signatures come from. When you copy a logo from a document or an email signature generator that doesn’t properly code inline images, the image is often embedded or even converted into base64. This leads to:

  • Signature image attachments
  • Large email size warnings
  • Unclickable logos
  • Display issues in Outlook or Gmail

Instead, always code the signature in proper HTML, using image tags that point to externally hosted files on a secure server (or use a signature management tool that handles this for you).

Pro Tip: Where to Host Inline Images

You don’t need a full CDN. Even hosting images on your main website’s server is fine as long as:

  • They’re served over HTTPS
  • You avoid large file sizes (ideally under 30–40KB per image)
  • The files aren’t accidentally deleted during a future website update

Avoid using file-sharing platforms like Google Drive or Dropbox — they don’t deliver direct image URLs suitable for email clients.

If you're building or managing professional HTML email signatures, go with inline (hosted) images nearly every time.

They’re lighter, more consistent, and easier to maintain across a team. Embedded images might seem appealing for their always-on delivery, but they come with too many downsides — especially in enterprise or customer-facing settings where deliverability and visual integrity matter.

Want to test your signature setup?
Send yourself an email in both Gmail and Outlook, reply to it, forward it, and open it on mobile. If the logo still looks perfect each time, you’ve done it right.

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Amy Lockwood is the Co-Founder of Email Signature Rescue with over a decade of experience in HTML email signatures for 60+ email clients, apps and CRM software including Outlook, Gmail, Apple Mail. She is the Head Designer of the Email Signature Rescue apps and website.

📩 Need help with your HTML email signatures? Contact Amy at emailsignaturerescue.com.

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