html-emails

An HTML email setup for transactional messages such as confirmations, sign-in links, and invitations. It adds inline CSS and a plain-text version so the same email can work across common mail apps.

In plain words
What is it for?
It helps build shared HTML email layouts, convert styles to inline CSS, generate text alternatives, and connect authentication or team invitation notifications to the HTML email pipeline.
Why use it?
Email clients handle CSS differently, which can break layouts. A plain-text alternative is also needed for recipients or systems that do not use HTML.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/fullstack-phoenix/saas_kit/html-emails
Any agent
npx skills add fullstack-phoenix/saas_kit --skill html-emails
Clone the repo
git clone --depth 1 https://github.com/fullstack-phoenix/saas_kit

Made for: Claude Code, Codex.

Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,087 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00042 $0.01087
Opus 5 $0.00021 $0.00544
Sonnet 5 $0.00008 $0.00217
Haiku 4.5 $0.00004 $0.00109

Measured yesterday against content hash c270f75d9c8a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

html-emails scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/html-emails/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HTML Emails

Adds a Swoosh-based HTML email pipeline backed by Premailex. Emails are written as HEEx templates wrapped in a shared layout, then premail/1 inlines the CSS and generates a plain-text alternative. This improves deliverability and consistent rendering in Gmail, Outlook, and Apple Mail. When authentication or teams are present, it also swaps their notifiers over to the HTML pipeline.

When to use

  • The app sends transactional email (confirmations, magic links, invites) and you want client-safe HTML with inline styles.
  • You need a plain-text fallback generated automatically for every email.
  • Don't reach for this if the app only sends raw text emails and rendering / deliverability isn't a concern — plain Swoosh is enough then.

Dependencies

  • Requires: None.
  • Recommended: None. Pairs naturally with authentication (user notifier) and teams (invitation notifier) — if either is installed, this feature upgrades their email templates automatically.

Install

mix saaskit.feature.install html_emails

No install decisions. The installer adds the premailex dep, the mailer helpers, the EmailHTML view, and the HTML/text layouts. Conditional templates are generated only when their feature is present: user notifier + auth email templates when authentication is installed, invitation notifier + invite template when teams is installed.

What it generates

  • mix.exs — injects {:premailex, "~> 0.3.20"} into deps.
  • lib/my_app/mailer.ex — Swoosh mailer with base_email/0, render_body/3 (renders a HEEx template inside the layout), apply_layout/1, and premail/1 (inline CSS + plain-text body).
  • lib/my_app_web/emails.exMyAppWeb.EmailHTML, embeds all templates under emails/*.html and emails/*.text.
  • lib/my_app_web/emails/layout.html.heex + layout.text.heex — shared HTML and text layouts (reset CSS, preheader, footer).
  • When authentication is installed: lib/my_app/users/user_notifier.ex plus user_confirmation_instructions, user_magic_link_instructions, and user_update_email_instructions HEEx templates.
  • When teams is installed: lib/my_app/teams/invitation_notifier.ex plus emails/invite_user.html.heex.

Read the full file on GitHub · 116 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 116 lines · 42 tokens per session scan A c270f75d9c8a

Subscribe to this mod's changes

html-emails is a skill published in the GitHub repository fullstack-phoenix/saas_kit (2 stars, last pushed 2mo ago), licensed MIT. It adds 42 tokens to every session and 1,087 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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