custom.sig
esignature os
Deliverability

Renders everywhere. Every time.

A signature is only as good as the client that renders it. We test against 40+ inbox/device combinations.

Email-safe HTML

Nested tables, inline CSS, no external JS. Same markup used by Fortune 500 email teams.

Mobile-perfect

Responsive layouts collapse gracefully on iOS and Android — no zoom, no overflow.

Dark mode ready

Foreground colors, logos, and dividers auto-invert in Apple Mail, Outlook and Gmail dark modes.

40+ client tests

Every template rendered against Gmail, Outlook 2016/365, Apple Mail, Yahoo, and mobile clients.

Anti-clipping

Signature markup stays under Gmail's 102KB clipping threshold — no 'view entire message' footer.

Fallback images

Every icon and logo ships with PNG fallbacks for clients that block SVG or web fonts.