Sending Emails

SubscribeFlow sends emails through Resend. You write templates in MJML, send transactional emails to individual recipients, and run campaigns to reach tagged segments of your subscriber base.

Templates

Templates use MJML for responsive email markup. Variables are inserted with {{variable_name}} syntax.

Create a template

PythonTypeScriptcURL

template = await client.templates.create(
    name="Welcome Email",
    subject="Welcome to {{company}}, {{name}}!",
    mjml_content="""
    <mjml>
      <mj-body>
        <mj-section>
          <mj-column>
            <mj-text>Hello {{name}}, welcome to {{company}}!</mj-text>
          </mj-column>
        </mj-section>
      </mj-body>
    </mjml>
    """,
    category="transactional",
)
print(f"Template created: {template.slug}")

const template = await client.templates.create({
  name: 'Welcome Email',
  subject: 'Welcome to {{company}}, {{name}}!',
  mjml_content: `
    <mjml>
      <mj-body>
        <mj-section>
          <mj-column>
            <mj-text>Hello {{name}}, welcome to {{company}}!</mj-text>
          </mj-column>
        </mj-section>
      </mj-body>
    </mjml>
  `,
  category: 'transactional',
});

console.log('Template created:', template.slug);

curl -X POST https://api.subscribeflow.net/api/v1/templates \
  -H "X-API-Key: sf_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Welcome Email",
    "subject": "Welcome to {{company}}, {{name}}!",
    "mjml_content": "<mjml><mj-body><mj-section><mj-column><mj-text>Hello {{name}}, welcome to {{company}}!</mj-text></mj-column></mj-section></mj-body></mjml>",
    "category": "transactional"
  }'

Preview a template

Render a template with sample variables before sending.

PythonTypeScriptcURL

preview = await client.templates.preview(
    "template-id",
    variables={"company": "Acme Inc", "name": "Alice"},
)
print(preview.html)

const preview = await client.templates.preview('template-id', {
  company: 'Acme Inc',
  name: 'Alice',
});

console.log(preview.html);

curl -X POST https://api.subscribeflow.net/api/v1/templates/TEMPLATE_ID/preview \
  -H "X-API-Key: sf_live_..." \
  -H "Content-Type: application/json" \
  -d '{"variables": {"company": "Acme Inc", "name": "Alice"}}'

Send a transactional email

Transactional emails go to a single recipient immediately.

PythonTypeScriptcURL

result = await client.emails.send(
    template_slug="welcome-email",
    to="alice@example.com",
    variables={"company": "Acme Inc", "name": "Alice"},
    idempotency_key="welcome-alice-2024",
)
print(f"Email queued: {result.id} (status: {result.status})")

const result = await client.emails.send({
  template_slug: 'welcome-email',
  to: 'alice@example.com',
  variables: { company: 'Acme Inc', name: 'Alice' },
  idempotency_key: 'welcome-alice-2024',
});

console.log('Email queued:', result.id);

curl -X POST https://api.subscribeflow.net/api/v1/emails/send \
  -H "X-API-Key: sf_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "template_slug": "welcome-email",
    "to": "alice@example.com",
    "variables": {"company": "Acme Inc", "name": "Alice"},
    "idempotency_key": "welcome-alice-2024"
  }'

Tip

Use idempotency_key to prevent duplicate sends. If you retry a request with the same key, SubscribeFlow returns the original result instead of sending again.

Campaigns

Campaigns send a template to all subscribers matching a tag filter. The workflow is: create a draft, configure the tag filter, preview the recipient count, and send.

Create a campaign

PythonTypeScriptcURL

campaign = await client.campaigns.create(
    name="March Newsletter",
    template_id="template-uuid",
    tag_filter={"include_tags": ["newsletter"], "match": "any"},
)
print(f"Campaign draft: {campaign.id}")

const campaign = await client.campaigns.create({
  name: 'March Newsletter',
  template_id: 'template-uuid',
  tag_filter: { include_tags: ['newsletter'], match: 'any' },
});

console.log('Campaign draft:', campaign.id);

curl -X POST https://api.subscribeflow.net/api/v1/campaigns \
  -H "X-API-Key: sf_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "name": "March Newsletter",
    "template_id": "template-uuid",
    "tag_filter": {"include_tags": ["newsletter"], "match": "any"}
  }'

Preview recipient count

Before sending, check how many subscribers will receive the campaign.

PythonTypeScriptcURL

count = await client.campaigns.count_recipients(
    include_tags=["newsletter"],
)
print(f"Will reach {count} subscribers")

const count = await client.campaigns.countRecipients('campaign-id');
console.log(`Will reach ${count.count} subscribers`);

curl https://api.subscribeflow.net/api/v1/campaigns/CAMPAIGN_ID/recipient-count \
  -H "X-API-Key: sf_live_..."

Send and monitor

PythonTypeScriptcURL

# Send
result = await client.campaigns.send("campaign-id")
print(f"Sending to {result.total_recipients} recipients")

# Check status later
campaign = await client.campaigns.get("campaign-id")
print(f"Status: {campaign.status}")

# Cancel if needed
await client.campaigns.cancel("campaign-id")

// Send
const result = await client.campaigns.send('campaign-id');
console.log(`Sending to ${result.total_recipients} recipients`);

// Check status later
const campaign = await client.campaigns.get('campaign-id');
console.log('Status:', campaign.status);

// Cancel if needed
await client.campaigns.cancel('campaign-id');

# Send
curl -X POST https://api.subscribeflow.net/api/v1/campaigns/CAMPAIGN_ID/send \
  -H "X-API-Key: sf_live_..."

# Check status
curl https://api.subscribeflow.net/api/v1/campaigns/CAMPAIGN_ID \
  -H "X-API-Key: sf_live_..."

# Cancel
curl -X POST https://api.subscribeflow.net/api/v1/campaigns/CAMPAIGN_ID/cancel \
  -H "X-API-Key: sf_live_..."

Email triggers

Triggers send an email automatically when a specific event occurs -- for example, a welcome email whenever a new subscriber is created.

PythonTypeScriptcURL

trigger = await client.triggers.create(
    event_type="subscriber.created",
    template_id="welcome-template-uuid",
    description="Send welcome email on signup",
)
print(f"Trigger active: {trigger.id}")

# Disable a trigger
await client.triggers.update("trigger-id", is_active=False)

const trigger = await client.triggers.create({
  event_type: 'subscriber.created',
  template_id: 'welcome-template-uuid',
  description: 'Send welcome email on signup',
});

console.log('Trigger active:', trigger.id);

// Disable a trigger
await client.triggers.update('trigger-id', { is_active: false });

curl -X POST https://api.subscribeflow.net/api/v1/triggers \
  -H "X-API-Key: sf_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "event_type": "subscriber.created",
    "template_id": "welcome-template-uuid",
    "description": "Send welcome email on signup"
  }'

Hands-On: Send your first campaign

Create a template, set up a campaign, and send it to your newsletter subscribers.

PythonTypeScriptcURL

import asyncio
from subscribeflow import SubscribeFlowClient

async def main():
    async with SubscribeFlowClient(api_key="sf_live_...") as client:
        # 1. Create a template
        template = await client.templates.create(
            name="First Newsletter",
            subject="Hello from {{company}}!",
            mjml_content="""
            <mjml>
              <mj-body>
                <mj-section>
                  <mj-column>
                    <mj-text font-size="20px">
                      Hello from {{company}}!
                    </mj-text>
                    <mj-text>
                      This is our first newsletter. Thanks for subscribing!
                    </mj-text>
                  </mj-column>
                </mj-section>
              </mj-body>
            </mjml>
            """,
            category="marketing",
        )

        # 2. Create a campaign
        campaign = await client.campaigns.create(
            name="First Newsletter",
            template_id=template.id,
            tag_filter={"include_tags": ["newsletter"], "match": "any"},
        )

        # 3. Preview recipients
        count = await client.campaigns.count_recipients(
            include_tags=["newsletter"],
        )
        print(f"Will send to {count} subscribers")

        # 4. Send
        result = await client.campaigns.send(campaign.id)
        print(f"Campaign sent to {result.total_recipients} recipients")

asyncio.run(main())

import { SubscribeFlowClient } from '@subscribeflow/sdk';

const client = new SubscribeFlowClient({
  apiKey: 'sf_live_...',
});

// 1. Create a template
const template = await client.templates.create({
  name: 'First Newsletter',
  subject: 'Hello from {{company}}!',
  mjml_content: `
    <mjml>
      <mj-body>
        <mj-section>
          <mj-column>
            <mj-text font-size="20px">
              Hello from {{company}}!
            </mj-text>
            <mj-text>
              This is our first newsletter. Thanks for subscribing!
            </mj-text>
          </mj-column>
        </mj-section>
      </mj-body>
    </mjml>
  `,
  category: 'marketing',
});

// 2. Create a campaign
const campaign = await client.campaigns.create({
  name: 'First Newsletter',
  template_id: template.id,
  tag_filter: { include_tags: ['newsletter'], match: 'any' },
});

// 3. Preview recipients
const count = await client.campaigns.countRecipients(campaign.id);
console.log(`Will send to ${count.count} subscribers`);

// 4. Send
const result = await client.campaigns.send(campaign.id);
console.log(`Campaign sent to ${result.total_recipients} recipients`);

# 1. Create a template (save the returned ID)
TEMPLATE_ID=$(curl -s -X POST https://api.subscribeflow.net/api/v1/templates \
  -H "X-API-Key: sf_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "name": "First Newsletter",
    "subject": "Hello from {{company}}!",
    "mjml_content": "<mjml><mj-body><mj-section><mj-column><mj-text>Hello from {{company}}!</mj-text></mj-column></mj-section></mj-body></mjml>",
    "category": "marketing"
  }' | jq -r '.id')

# 2. Create a campaign
CAMPAIGN_ID=$(curl -s -X POST https://api.subscribeflow.net/api/v1/campaigns \
  -H "X-API-Key: sf_live_..." \
  -H "Content-Type: application/json" \
  -d "{
    \"name\": \"First Newsletter\",
    \"template_id\": \"$TEMPLATE_ID\",
    \"tag_filter\": {\"include_tags\": [\"newsletter\"], \"match\": \"any\"}
  }" | jq -r '.id')

# 3. Send
curl -X POST "https://api.subscribeflow.net/api/v1/campaigns/$CAMPAIGN_ID/send" \
  -H "X-API-Key: sf_live_..."