Format: PNG (or JPG)
Use PNG for logos, or JPG if the logo sits on a solid background. Avoid SVG — many email clients, including Gmail and Outlook, do not display it. WebP is also not supported everywhere in email.
Size
- Display width in the signature: usually 120–250 px.
- Export the file at twice that width (for example 400 px wide) so it stays sharp on high-resolution screens, and set the display width in the signature editor.
- Keep the file small — ideally under 50 KB. Use Resize image and Compress image.
Dark mode
In dark mode, a dark logo on a transparent background can almost disappear. Two safe options: give the logo a solid light background with rounded corners, or add a thin light outline around dark elements. Test by sending an email to yourself and viewing it on a phone in dark mode.
Logo with a white box?
If your only logo file has a white rectangle, remove it with the logo background remover — it also cleans the white halo around the edges.
Frequently asked questions
Why is my signature logo shown as an attachment?
Some apps show embedded images as attachments. Hosting the image on your website and inserting it by URL usually avoids this, though some recipients block remote images by default.