How to Add a Logo to Your Email Signature Without It Showing as an Attachment

You added your company logo to your email signature. It looked perfect in the preview. Then you sent an email and your recipient saw this:

"image001.png (15 KB)" attached to your message.

Instead of a polished, branded signature, your logo is dangling at the bottom of the email as a file attachment. It looks unprofessional, confuses recipients, and clutters their inbox.

Here's why this happens and how to fix it permanently.

Why Logos Show as Attachments

There are three common causes:

1. The Image Is Embedded, Not Hosted

When you paste an image from your desktop into Outlook's signature editor, Outlook embeds the image file directly into the email. Technically, it's an inline attachment using a CID (Content-ID) reference.

While this works in some email clients, many others (especially mobile apps) display embedded images as attachments.

2. The Image Is Base64-Encoded

Some signature generators or email tools encode images as base64 strings directly in the HTML. This makes the email larger and many email clients (including Outlook) strip or mishandle base64 images.

3. Outlook's "Send as Attachment" Behaviour

Outlook has a setting that can convert inline images to attachments, especially when:

• The recipient's email client requests plain text
• The email is forwarded multiple times
• The email passes through certain corporate email gateways

The Fix: Host Your Logo on a CDN

The only reliable way to prevent the attachment problem is to host your logo on a web server and reference it with a URL.

Instead of embedding the image file, your signature HTML should look like this:

<img
  src="https://res.cloudinary.com/yourcompany/logo.png"
  width="150"
  height="50"
  alt="Company Logo"
/>

When the email is opened, the recipient's email client downloads the image from the URL — just like a web browser loads images on a website. No attachment, no CID, no base64.

Where to Host Your Logo

Free options:

• Cloudinary — free tier includes 25GB storage
• Imgur — simple image hosting (less professional)
• Your company website — upload to /images/logo.png

Important: Use HTTPS URLs. Some email clients block HTTP images.

Recommended Image Settings

Setting	Recommendation
Format	PNG (for logos with transparency) or JPG
Max file size	Under 100KB
Dimensions	150-300px wide, proportional height
Resolution	144 DPI (for retina displays)
Background	Transparent (PNG) if your logo needs it

Step-by-Step: Fix Your Outlook Signature

Step 1: Upload Your Logo

1. Go to Cloudinary (or your hosting platform)
2. Upload your logo
3. Copy the URL (it should start with https://)

Step 2: Update Your Signature in Outlook

1. Go to File > Options > Mail > Signatures
2. Select your signature
3. Delete the existing logo image
4. Click Insert Picture (the image icon)
5. Paste your hosted URL (not a file path)
6. Click Insert

Step 3: Set Image Dimensions

1. Right-click the inserted image
2. Select Format Picture or Size
3. Set the width to your desired size (e.g., 150px)
4. Ensure "Lock aspect ratio" is checked
5. Click OK

Step 4: Test It

1. Send a test email to a Gmail account
2. Send a test to a colleague on Outlook
3. Check both on desktop and mobile
4. Verify the logo displays inline, not as an attachment

Step-by-Step: Fix Your Gmail Signature

Gmail handles this slightly differently:

1. Open Gmail Settings > Signature
2. Click the image icon in the signature editor toolbar
3. Select Web Address (URL)
4. Paste your hosted logo URL
5. Click Select
6. Resize if needed by clicking the image and choosing Small, Medium, or Large

Gmail typically handles hosted images well, but always test.

What About PNG Transparency?

If your logo has a transparent background (common for logos used on both light and dark backgrounds), use PNG format. JPG doesn't support transparency.

Tip: Some email clients (older Outlook versions) may show a white background behind transparent PNGs. To be safe, design your logo to look good on both white and coloured backgrounds.

Common Mistakes

1. Using a file path — C:\Users\Desktop\logo.png won't work for anyone but you
2. Using Google Drive links — these require authentication and won't display
3. Using SVG format — email clients don't support SVG; use PNG instead
4. Too large an image file — anything over 200KB slows down email loading and may be flagged as spam
5. Not setting dimensions — without explicit width/height, the logo may display at full size

The Automatic Solution

If all of this sounds like too much work, SendSignatures handles it automatically:

1. Upload your logo in the editor
2. It's automatically hosted on our CDN (Cloudinary)
3. Optimised for email (correct format, size, and compression)
4. Referenced by URL in your signature HTML
5. Never shows as an attachment

This is included in the Pro plan — one-time payment, lifetime access, no subscriptions.

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Ready to fix your logo problem for good? Create your signature now — free to start.