How to Build an Email Signature That Survives Gmail, Outlook and Apple Mail
By the Super Simple Digital Tools Team · Updated June 2026
Email clients are not browsers. Gmail, Outlook and Apple Mail each render HTML with their own quirks, so a signature built like a web page often falls apart on arrival. The most reliable approach is a table-based layout with styles written inline on each element, which is exactly what this generator produces. Modern CSS like flexbox or external stylesheets gets stripped or ignored, but old-fashioned tables with inline styling render predictably almost everywhere, which is why professional signature tools still rely on them.
Keep the dimensions sensible. A signature roughly 300 to 600 pixels wide and 150 to 200 pixels tall holds your details comfortably without dominating the message or breaking on small screens. Because the majority of email is now read on phones, check that your font size stays legible on mobile and that nothing forces horizontal scrolling. Stick to one or two fonts and your brand colors; mixing several typefaces or script fonts reads as cluttered and is harder to scan on a small display.
Images are where most signatures break. Never paste a logo straight from your computer, that tends to attach the file or vanish when the email converts to plain text. Instead host the image on a stable HTTPS server and reference it by URL. Avoid Base64-embedded images: they inflate the email, some clients including Gmail refuse to display them, and security filters can treat large encoded blocks as suspicious. To prevent blur, export the image at the exact pixel size it will display, or at 2x for retina screens, rather than letting the client resample it.
Pasting matters as much as building. In Gmail, open Settings, See all settings, General, and paste into the Signature field; in Outlook, find Signatures under Mail settings and paste there. Copying the signature in Google Chrome tends to preserve the underlying table structure most faithfully. Apple Mail is fussier, you may need to turn off "Always match my default message font" before the formatting sticks, and iOS often sends in plain text, which can drop images entirely.
Finish by testing, not assuming. Send the signature to yourself and to a colleague, then open it on a desktop client and a phone, and check a reply and a forward too, since spacing and images frequently shift there. Confirm every link works and points to HTTPS. Once it looks right across the clients your recipients use, lock it in and update it only when your title, phone number or links actually change.
- Host your logo or headshot on a public HTTPS URL and link to it, never paste the image file directly into the signature box.
- Limit yourself to one call-to-action and one or two contact methods; a packed signature creates clutter and lowers the chance anyone acts on it.
- Export images at their exact display size (or 2x for retina) to avoid the blur that comes from clients resampling oversized files.
- Always send a test email and check it on both desktop and mobile, including how it looks in a reply, before rolling the signature out.