The newsletter is the brand's longest-form owned channel. It arrives in an inbox as a letter, not a feed post, and gets read at whatever width the reader's client allows. Substack is the current platform; a switch changes the settings, not the guidance. The studio team owns it.
Identity here
- Logo: the square publication logo takes the avatar variant. No existing lockup fits the wordmark slot's wide ratio. That export is requested from design. Variants: 4.1 Logo.
- Colour: the header banner and designed imagery carry the brand palette; body text stays on the platform's reading defaults rather than fighting them: 4.2 Colour.
- Type: designed assets (header, feature images) use the brand type roles. Body copy renders in the platform's email-safe stack, the same constraint the Email Signature works under: 4.3 Typography.
Specs
| Asset | Size | Safe area | Format | Max weight | Notes |
|---|---|---|---|---|---|
| Publication logo | 256×256 minimum (1:1) | square crop, centre the mark | PNG (transparent) / JPG | – | avatar logo variant |
| Wordmark | 1344×256 minimum (21:4) | – | PNG (transparent) | – | no existing lockup fits 21:4. Export requested from design |
| Header banner | 1100×220 (5:1) | keep content centred | PNG (transparent) / JPG | keep light. It loads in email | tops every sent email |
| Cover image | 600×600 minimum (1:1) | – | PNG/JPG | – | the publication's directory card |
| Post feature image | 1456×1048 | focal point centred | PNG/JPG | ~150 KB working target | doubles as the post's social preview |
| Inline images | 1600px wide upload; renders at 800px | body crops anything taller than square | PNG/JPG/GIF | keep light | 2× upload keeps retina sharp |
Specs verified against platform documentation: 2026-07-05.
Substack publishes the dimensions but no hard file-size caps. The weights above are deliverability targets, not platform limits. Heavy images are the difference between a newsletter that opens and one that gets clipped mid-scroll.
Templates & assets
Header-banner and feature-image blanks at spec size, plus the wide wordmark export, are requested from design. Each frame below holds its format at the exact ratio until the template lands.
Header banner, 1100×220 (5:1)
Post feature image, 1456×1048
Wide wordmark, 1344×256 (21:4)
Don't
Don't publish without a feature image
The feature image is the social preview. Without one, every share of the post renders as a bare link. The platform decides how the brand looks.
Don't send heavy images
Mail clients clip long, heavy emails. An oversized inline image can cut the letter off before the sign-off, and the reader never knows.
Don't rely on tall imagery
The body crops anything taller than square. A portrait composition loses its top and bottom. Design inline images landscape or square.
Voice here
A newsletter is read, not scrolled past. It earns the space for full arguments, in the same register as everything else: 3.3 How We Communicate. Subject lines follow the headline rule: an argument, not a label.
Tools
- Image Placeholder, draft-stage imagery at exact header and feature dimensions
Checklist
- Feature image present at 1456×1048, focal point centred
- Inline images landscape or square, uploaded at 2×, kept light
- Logo and wordmark slots carry the correct variants
- Subject line is an argument, not a label; body passes the voice check
- Test send checked in a real mail client before publishing