Email

Synapse sends email through its own isolated SMTP transport — never the host app's mailer or global mail config. The transport is configured in the admin Settings screen, the body of an email is any page tagged kind=email, and a send_email flow node fires it. This keeps a built app's email fully self-contained and portable across host apps.

SMTP settings

Configured on the Settings admin page (PageBuilderSettings) and stored via the Settings service in page_builder_settings. Keys:

Setting key	Meaning
`mail_host`	SMTP server hostname (e.g. `smtp.example.com`)
`mail_port`	SMTP port (default 587)
`mail_username`	SMTP username (optional — omitted from the DSN if unset)
`mail_password`	SMTP password — encrypted at rest (`Settings::setEncrypted`/`getEncrypted`)
`mail_encryption`	`tls` (STARTTLS), `ssl` (implicit TLS), or `''` (none)
`mail_from_address`	Sender address
`mail_from_name`	Sender display name (optional)

The password field on the Settings form shows a masked placeholder and is only overwritten when you type a new value (leaving it blank keeps the stored one).

The isolated transport

src/Services/PageBuilderMailer.php builds a fresh Symfony Mailer transport on every send — it never mutates config('mail') or borrows the host mailer, so a builder send can't interfere with the surrounding application.

configured() → true once mail_host and mail_from_address are set.
The DSN is assembled by hand: scheme smtps:// when mail_encryption=ssl (implicit TLS), otherwise smtp:// (Symfony negotiates STARTTLS). Credentials are URL-encoded and omitted entirely when no username is set: {scheme}://{user}:{pass}@{host}:{port}.
The password is read back through Settings::getEncrypted('mail_password') so it is never held in plaintext at rest.

Send a test email

On the Settings page, the Send test email header action (visible once configured()) opens a prompt for an address and calls PageBuilderMailer::sendTest($to) — a one-line "Your Page Builder SMTP settings work" message. Use it to confirm the transport before wiring a flow.

Email-template pages (`kind=email`)

There's no separate email-authoring surface — an email body is a page with kind = 'email'. Build it like any page (you can use the editor), then reference it by slug from a send_email node. The page's css is inlined as a <style> block ahead of its html.

Mark a page as an email template by setting kind to email in the Pages form (the emailTemplates() scope lists them). The AI applier also auto-marks any page referenced as a send_email template, even if the plan forgot to tag it.

The `send_email` flow node

src/Flow/Nodes/SendEmailNode.php. Config:

json

{ "type": "send_email", "config": {
        "to": "{{ input.record.email }}",
        "subject": "Welcome {{ input.record.name }}",
        "template": "welcome-email",
        "body": "<p>Inline fallback when no template.</p>",
        "cc": "ops@example.com",
        "bcc": "",
        "reply_to": "",
        "output": "email"
      } }

to — required; string (comma-separated) or array; interpolated.
template — slug of a kind=email page used as the body. If omitted/not found, falls back to the inline body.
cc / bcc / reply_to — optional; interpolated; cc/bcc accept lists.
output — context var that receives the result (default email).

Non-fatal by design: a missing recipient, empty body, or unconfigured transport records { "sent": false, "error": "..." } in the output var and the flow continues; a successful send records { "sent": true }.

Mustache interpolation in templates

The body (template page HTML or inline body) is interpolated against the flow context before sending — using {{ ... }} tokens, not Alpine (emails have no JS):

Token	Resolves to
`{{ input.x }}`	The trigger input
`{{ vars.x }}`	A var a prior node wrote
`{{ states.x }}`	A persistent State

For a collection-triggered flow the changed row is at {{ input.record.<field> }} (plus {{ input.event }} and {{ input.collection }}). A typical "email on signup" template:

html

<h1>Welcome {{ input.record.name }}</h1>
      <p>Thanks for joining — we'll be in touch at {{ input.record.email }}.</p>

Pattern: notify on a record event

Create a kind=email page (e.g. welcome-email).
Create a flow with trigger_type: "collection", trigger_config: { "collection": "signups", "events": ["created"] }.
Add a send_email node whose template is welcome-email and to is {{ input.record.email }}.

See Flows → Collection trigger. This is exactly the example the AI emits for "a waitlist that emails a welcome on signup" — see AI.

Next: AI.