Short answer:
Use JPG for best compatibility.
PNG and GIF also work well, but SVG is not supported by most email clients, including Outlook.
Recommended image formats
JPG (recommended)
- Best overall compatibility across all email clients
- Ideal for photos and complex images
- Use the image in 100% dimensions (do not scale height and width)
- Always include height and width attributes (use the built-in designer)
PNG
- Supports transparency
- Good for logos and graphics
- Slightly larger file size than JPG
GIF
- Use for animated images
- Supported by most email clients
- Keep animations subtle and file size low
Why SVG is not supported
SVG (Scalable Vector Graphics) is not supported in most email clients, including Outlook, Gmail, and Apple Mail.
This is due to both security and technical limitations:
- Security risks: SVG files can contain embedded scripts (JavaScript), which can be used maliciously. Email clients block SVG to protect users.
- Rendering inconsistencies: Many email clients do not fully support SVG rendering, which can result in broken or missing images.
- Blocked by email clients: Outlook (desktop and web) and several other clients simply do not display SVG images at all.
- Spam filtering: Emails containing SVG images are more likely to be flagged or filtered by email security systems.
SVG images are not recommended for email signatures
Even though SVG provides high-quality, scalable graphics, it is not suitable for email signatures. Most email clients block or do not render SVG files, which means recipients may not see the image at all.
Best practice
- Use JPG for maximum compatibility
- Use PNG for logos requiring transparency
- Use GIF only when animation is needed
- Avoid SVG in all email signature use cases
