How to Add a Logo to Your Email Signature (Without It Looking Terrible)

Adding a logo to your email signature should be simple — but in practice, it's the #1 thing that goes wrong. Logos that are too big, too blurry, that appear as attachments, or that don't show at all. Here's how to get it right.

The Right File Format

Not all image formats work equally well in email signatures:

• PNG — Best choice for most logos. Supports transparency, crisp edges, and works in all email clients. Use PNG for logos with text, sharp lines, or transparent backgrounds.
• JPEG/JPG — Good for photographic images or headshots. Doesn't support transparency, so you'll get a white rectangle around your logo if it's not rectangular. Avoid for logos.
• GIF — Supported everywhere but limited to 256 colours. Fine for simple logos but PNG is almost always better.
• SVG — ❌ Not supported in most email clients. Never use SVG in email signatures.
• WebP — ❌ Not widely supported in email clients yet. Avoid.

Bottom line: Use PNG with a transparent background for your logo.

The Right Size

This is where most people go wrong. Your logo needs to be large enough to be sharp on retina/HiDPI screens, but displayed at a reasonable size in the signature:

• Display size: 100–200px wide is the sweet spot for most logos
• File resolution: Export at 2x the display size (so 200–400px actual width) for retina sharpness
• Height: Keep the displayed height under 80px — tall logos are distracting
• File size: Under 50KB for fast loading. Under 100KB is acceptable.

Hosting Your Logo

There are two ways to include a logo in your email signature, and one is clearly better:

Option 1: Externally Hosted (Recommended)

Upload your logo to a reliable image host and reference it by URL. This keeps your email small and avoids the "phantom attachment" problem. Good hosting options:

• Your company website (e.g. yourcompany.com.au/logo.png)
• Cloud storage with a public link (Google Drive, Dropbox — but make sure it's a direct link)
• Image CDNs (Cloudinary, Imgix)

Option 2: Embedded/Attached (Avoid)

Some email clients embed logos as CID (Content-ID) attachments. This means:

• Every email you send is larger
• Recipients see a paperclip / "1 attachment" indicator
• Some corporate email filters block or strip embedded images

Common Logo Mistakes

1. Using a massive file — A 2MB logo file makes every email slow to send and download. Compress it.
2. No transparent background — A white box around your logo on a dark email looks amateur. Export with transparency.
3. Scaling up a low-res logo — If your logo is blurry, you need a higher-resolution source file. Don't scale up — always scale down.
4. Different logos across the team — Old versions, wrong colours, outdated taglines. Standardise on one file hosted in one place.
5. Linking to an unstable URL — If your logo disappears tomorrow, every email you've ever sent will show a broken image icon. Use a reliable host.