feat(messaging): add a skill that offers and sets up transactional emails by mayteio · Pull Request #125415 · PostHog/posthog

mayteio · 2026-10-29T12:12:13Z

Problem

When a user tells an agent "our password resets go through Resend" or "we send receipts with Postmark", nothing in PostHog's skills or MCP tools brings up PostHog transactional emails.
The only transactional tool, workflows-make-email-template-transactional, fires only when a user already asks for it, and it stops there. Nothing guides the full setup: sender, template, key, code, status.

Changes

New skill sending-transactional-emails in products/messaging/skills/. Its description triggers on:
- transactional email, or password reset, sign-in code, magic link, verification, receipt and invite emails;
- the providers that send them: Resend, Postmark, SendGrid, Mailgun, Amazon SES, Mandrill, Loops, Brevo, Customer.io transactional, nodemailer or SMTP.
It fires whether the user sets one up, moves one, debugs one, or only describes their current setup.
The skill offers PostHog once, says what changes for the user, states the limits honestly, and drops the topic if the user declines.
It checks that the make-transactional tool is available before it promises anything, so projects without the flag or the scope don't get a pitch they can't use.
It walks through the setup with existing tools and skills:
- the verified sender via integrations-list, created in the conversation with integrations-email-create when that tool is available (feat(integrations): add an email sender over MCP #125535), or through building-workflows otherwise;
- the template via designing-email-templates;
- the category check, the make-transactional tool, and the project secret API key, which only the user can create;
- SDK or HTTP code with distinct IDs and idempotency keys;
- a test send and a status check.
references/moving-from-other-providers.md maps each provider's send call to emails.send, and lists what to check before a switch: sender, suppressions, error codes, retries and volume.
building-workflows routes a one-off email from code to the new skill.
installing-posthog-in-a-codebase mentions transactional emails once after setup, when the manifest has an email sending package.
The make-transactional MCP tool now names the steps that are left: the key, emails.send or the send route, and emails.get or the status route.
Mechanical: the regenerated MCP tool definition JSON files.

No change to the cdp_functions destination nudge: it is about moving marketing automation to Workflows, and the new skill's trigger covers transactional providers.

How did you test this code?

Test rationale: no new tests. These are prose skills and a tool description, which the skill linter and the build check.

hogli lint:skills passes, with no warnings on the changed skills.
hogli build:skills builds 171 skills, and the archive contains the new skill and its reference.
hogli product:lint messaging passes.
hogli build:openapi regenerated the MCP tool definitions. Only the make-transactional tool's description changed.

Not checked: the skill in a live agent session with hogli sync:skill.

Release status

This change is behind a feature flag and is not available to users

The make-transactional tool and the transactional email API are behind workflows-transactional-email-api. The skill checks that the tool is available before it offers anything. Merge it around when the flag opens to every project.

Docs update

None. The skill links to the transactional email docs page in PostHog/posthog.com#21564.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Agent: PostHog Desktop (Claude Code), Claude Opus 5.5

Skills: /writing-skills, /writing-pr-descriptions.
Started from an audit of the MCP tools and skills for transactional email. The audit found one flag-gated tool and no skill that triggers on the topic.
Duplicate search: no open PR adds a transactional email skill.
Public artifact: no session material is in the diff.

🤖 Generated with Claude Code

Created with PostHog Desktop

…ails - New sending-transactional-emails skill. It triggers on any mention of transactional email or a provider that sends it, offers PostHog once, and walks through the sender, template, make transactional, API key, SDK code and status checks. A reference maps other providers' send calls to PostHog. - building-workflows routes one-off emails from code to the new skill. - installing-posthog-in-a-codebase mentions transactional emails once when the app has an email sending package. - The make transactional MCP tool names the steps that are left. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Generated-By: PostHog Desktop Task-Id: e72a2c10-f145-4f7c-8754-a4fcc06a18be

trunk-io · 2026-10-29T12:12:18Z

😎 Merged successfully - details.

github-actions · 2026-10-29T12:13:40Z

🤖 CI report

⚠️

Trunk lane — backend Python lane

This PR is assigned to the backend Python lane. It runs backend Python tests and may merge in parallel with PRs in other lanes.

ℹ️ MCP UI apps size — 35 app(s), 29122.2 KB JS

Built size of each MCP UI app (main.js + styles.css).

App	JS	CSS
debug	844.3 KB	211.6 KB
explain-chart	1117.7 KB	211.6 KB
action	767.7 KB	211.6 KB
action-list	835.3 KB	211.6 KB
cohort	766.7 KB	211.6 KB
cohort-list	834.3 KB	211.6 KB
email-template	766.6 KB	211.6 KB
error-details	771.6 KB	211.6 KB
error-issue	768.9 KB	211.6 KB
error-issue-list	836.8 KB	211.6 KB
experiment	832.4 KB	211.6 KB
experiment-list	836.1 KB	211.6 KB
experiment-results	835.0 KB	211.6 KB
feature-flag	834.7 KB	211.6 KB
feature-flag-list	838.4 KB	211.6 KB
feature-flag-testing	770.0 KB	211.6 KB
inline-scan	767.2 KB	211.6 KB
insight-actors	833.8 KB	211.6 KB
llm-costs	831.1 KB	211.6 KB
session-recording	769.0 KB	211.6 KB
survey	768.3 KB	211.6 KB
survey-global-stats	831.1 KB	211.6 KB
survey-list	836.0 KB	211.6 KB
survey-stats	831.1 KB	211.6 KB
trace-span	767.1 KB	211.6 KB
trace-span-list	835.2 KB	211.6 KB
vision-observation-list	834.4 KB	211.6 KB
workflow	767.1 KB	211.6 KB
workflow-list	834.7 KB	211.6 KB
workflow-setup-status	766.7 KB	211.6 KB
query-results	1089.6 KB	211.6 KB
render-ui	1194.2 KB	211.6 KB
visual-review-snapshots	771.6 KB	211.6 KB
workflow-data-suggestions	769.4 KB	211.6 KB
workflow-sending-rules	768.1 KB	211.6 KB

ℹ️ MCP agent API — agent-facing tool changes

What this PR changes for agents, from the tool schema snapshots and tool definitions.

Tools changed (2):

Tool	Params	Scopes	Annotations	Schema chars
`workflows-make-email-template-transactional-execute`			description changed
`workflows-make-email-template-transactional-prepare`			description changed

parameterai · 2026-10-29T12:29:37Z

Risk: No findings

This change adds prose only: a new sending-transactional-emails skill with a provider-migration reference, small routing edits to two existing skills, and an expanded MCP tool description for workflows-make-email-template-transactional (plus its regenerated JSON). No executable code, endpoints, auth, or data handling changes, and the send/status endpoints the text references are pre-existing and untouched.

_{Sentinel reviewed 988a582 · Review settings}

pr-assigner-resolver-posthog · 2026-10-29T12:30:30Z

👀 Auto-assigned reviewers

These soft owners were skipped because they only have minor changes here. Nothing blocks merge, so self-assign if you'd like a look:

@PostHog/team-growth (products/wizard/product.yaml)

Soft owners come from each directory's owners.yaml and each product's product.yaml (resolved nearest-file-wins). For a skipped owner, the locator is the file that decided it. Generated files and lockfiles are ignored when deciding ownership.

posthog

PostHog Review · Standard · reviewed 988a582: 3 Should fix.

This Standard review started from the posthog-review label. Comment @posthog review --deep for a Deep review, or @posthog help to see all commands.

See this review and its findings in PostHog Review.

…ional email skill - Ask for the user's website or a current email before designing, so the first template matches their brand. - Reuse the app's client, keep the SDK's error, retry an uncertain outcome with the same key, and handle status read errors and not_found. - Format the provider table with oxfmt. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Generated-By: PostHog Desktop Task-Id: e72a2c10-f145-4f7c-8754-a4fcc06a18be

trunk-io · 2026-10-29T13:01:24Z

_{View Full Report ↗︎ ⋅ Docs}

- Check for the registered prepare and execute tool pair, and describe the confirmation sequence. - Check engagement capture before promising person events, and offer to turn it on. - Limit the idempotency guarantee to the 24 hour key window. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Generated-By: PostHog Desktop Task-Id: e72a2c10-f145-4f7c-8754-a4fcc06a18be

hosthog · 2026-10-29T16:28:00Z

HostHog preview — `posthog-desktop-web`

The previews for this PR have been torn down and no longer serve.

… skill When `integrations-email-create` is available, the skill creates the sender, shows the DNS records, and verifies the domain without sending the user to the app. Otherwise it falls back to the building-workflows skill. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Generated-By: PostHog Desktop Task-Id: e72a2c10-f145-4f7c-8754-a4fcc06a18be

A new stamphog review started for this PR — the fresh verdict replaces this approval.

…kill The HTTP line now lists template_id and distinct_id at the top level, matching #126287. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Generated-By: PostHog Desktop Task-Id: e72a2c10-f145-4f7c-8754-a4fcc06a18be

A new stamphog review started for this PR — the fresh verdict replaces this approval.

stamphog

Approved.

Contained skill documentation and tool-description changes; existing permissions, confirmation requirements, and API behavior remain unchanged. The older review supplies no specific concerns to verify, and no substantive blocking concerns are present in the supplied context.

Author wrote 20% of the modified lines and has 14 merged PRs in these paths (familiarity MODERATE).

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	13L, 3F substantive, 139L/7F incl. docs/generated/snapshots — within ceiling
tier	✓	T1-agent / T1c-medium (139L, 7F, two-areas, feat)
stamphog 2.6.1		`.stamphog/policy.yml` @ `6d4fd46` · reviewed head `6d4fd46`

mayteio · 2026-11-02T12:19:31Z

/trunk merge

deployment-status-posthog · 2026-11-02T13:17:35Z

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-11-02 13:17 UTC	Run
prod-us	✅ Deployed	2026-11-02 13:43 UTC	Run
prod-eu	✅ Deployed	2026-11-02 13:36 UTC	Run

mayteio self-assigned this Oct 29, 2026

mayteio marked this pull request as ready for review October 29, 2026 12:29

mayteio added the posthog-review label Oct 29, 2026

pr-assigner-resolver-posthog Bot requested a review from a team October 29, 2026 12:30

posthog Bot reviewed Oct 29, 2026

View reviewed changes

Comment thread products/messaging/skills/sending-transactional-emails/SKILL.md Resolved

Comment thread products/messaging/skills/sending-transactional-emails/SKILL.md Resolved

Comment thread products/messaging/skills/sending-transactional-emails/SKILL.md Resolved

posthog Bot removed the posthog-review label Oct 29, 2026

mayteio added the stamphog Request AI approval (no full review) label Oct 29, 2026

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This was referenced Oct 29, 2026

chore(skills): reserve the send-transactional-email skill name Silthus/posthog#572

Closed

Map: send code-managed email templates with one PostHog call Silthus/posthog#461

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stamphog Bot approved these changes Oct 30, 2026

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Silthus mentioned this pull request Nov 2, 2026

feat(transactional-email): add a command that sets up the first email send PostHog/wizard#1507

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trunk-io Bot merged commit 2a69aa7 into master Nov 2, 2026
211 checks passed

trunk-io Bot deleted the posthog/messaging-transactional-email-skill branch November 2, 2026 12:51

Silthus mentioned this pull request Nov 3, 2026

feat(skills): publish sending-transactional-emails for the Wizard PostHog/context-mill#456

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