Email for your entire customer journey
Send lifecycle and transactional email from one platform, alongside your in-app, push, SMS, and chat messages.
Send email via SendGrid, Postmark, Amazon SES, and more
Connect your email provider(s) and use Knock to trigger emails via audience membership, product events, and API calls, with full deliverability and engagement analytics at your fingertips.
Audience membership waits one hour, then an email step sends one template through SendGrid, Postmark, Resend, Amazon SES, or Mailgun. Each send adds a new email to the top of the recipient's inbox, and earlier ones move down.
Granular control over every email sent
Knock gives you granular control over email delivery, with templates, layouts, and provider connections managed in one place.
AI-powered template editor
Never build an email from scratch again. Generate engaging, on-brand templates with a prompt, and then edit via HTML, CSS, MJML, or the drag-and-drop visual editor.
Emails in your design system
Put an end to off-brand content drift. Set global styles, build a library of shared layouts and reusable content blocks, and render live client previews to move faster while ensuring consistent, on-brand emails.
Personalized messaging
Eliminate generic messaging. Personalize every email with user variables and Liquid conditions, and use AI to enrich data, qualify recipients, and summarize context before you send.
Advanced sending functions
Batch, delay, and throttle emails, so five new comments go out as one digest instead of five separate emails. Run A/B tests to learn what works best for your audience.
User-first preference controls
A branded preference center enables users to choose which emails they receive by category or workflow, and Knock checks those preferences before each send.
Understand every interaction
Track delivery, opens, clicks, and unsubscribes across providers. Check message logs and rendered HTML previews to understand what each user received.
Launch email flows with a prompt
Pick your agent and a use case, then use the prompt to build it.
Your agent
Use case
Your prompt
Prompt
Build an email onboarding series for new signups using Knock. Based on what we're building, send a welcome email on day 0 and a setup tips email on day 3 if they have not finished setup.
All starter prompts, for people and agents
Connect your agent to the Knock MCP server at https://mcp.knock.app/mcp, or install the Knock CLI with npm install -g @knocklabs/cli. Then use any prompt below.
- Knock: Build in Knock
- Claude: First make sure to install the Knock connector.
- ChatGPT: First make sure to install the Knock plugin.
- Cursor: First make sure to install the Knock plugin.
- Grok: First make sure to install the Knock plugin.
- Slack: First make sure to connect Knock in Slack.
- MCP: First make sure to connect the Knock MCP server.
- CLI: First make sure to install the Knock CLI.
Onboarding (Lifecycle)
Build an email onboarding series for new signups using [Knock](https://knock.app). Based on what we're building, send a welcome email on day 0 and a setup tips email on day 3 if they have not finished setup.
Re-engagement (Lifecycle)
Find users with no activity in the last 30 days. Based on what we're building, create a re-engagement email using [Knock](https://knock.app). Stop the sequence as soon as a user signs in.
Trial ending (Lifecycle)
When a trial has 3 days left. Based on what we're building, create an email using [Knock](https://knock.app) with an upgrade button. Stop as soon as the account upgrades.
Receipts (Transactional)
Based on what we're building, create a workflow using [Knock](https://knock.app) that sends an email receipt with the order or payment details right after a payment succeeds.
Password reset (Transactional)
When a user requests a password reset. Based on what we're building, create an email using [Knock](https://knock.app) that sends the reset link right away.
Invitations (Transactional)
When a user invites a teammate. Based on what we're building, create an invitation email using [Knock](https://knock.app) with a link to join, and send a reminder 2 days later if they haven't joined.
Weekly digest (Product)
Based on what we're building, create a workflow using [Knock](https://knock.app) that batches each user's activity from the past week into one digest email. Skip the email when there is no new activity.
Comment digest (Product)
When a post gets new comments. Based on what we're building, create a workflow using [Knock](https://knock.app) that batches them for an hour and sends one email per post instead of one email per comment.
Feature launch (Promotional)
Based on what we're building, create a broadcast using [Knock](https://knock.app) that sends an email announcing a new feature to users who opted in to product updates.
Messaging infrastructure you can trust
99.99% uptime
We run Knock as critical infrastructure for your product.
Scaled delivery
Knock delivers hundreds of millions of messages per month.
Dedicated success
Our team helps you plan, build, and launch your messaging.
Secure access
Security is standard with support for SSO, RBAC, and SCIM.
HIPAA
SOC2
GDPR
CCPA
Compare email API benchmarks
See real-time performance, reliability, and uptime benchmarks for top email providers, powered by proprietary data from billions of messages sent through Knock.
| Provider | Message volume | Median response time | Error rate | Growth |
|---|---|---|---|---|
 | 100M–500M | 14ms | 0.00% | 2nd |
 | 10M–25M | 60ms | 0.00% | 4th |
 | 1M–10M | 76ms | 0.00% | 1st |
 | <1M | 82ms | 0.00% | 9th |
 | 100M–500M | 122ms | 0.00% | 5th |
 | 100M–500M | 167ms | 0.00% | 3rd |
 | <1M | 266ms | 0.00% | 8th |
 | <1M | 305ms | 0.00% | 7th |
 | <1M | 319ms | 0.00% | 10th |
 | <1M | 405ms | 0.00% | 6th |
Frequently asked questions
Knock sends email through SendGrid, Postmark, Amazon SES, Mailgun, Mailjet, Mailtrap, MailerSend, Mandrill, SparkPost, Resend, and Cloudflare. Each environment has its own channel settings, so development and production can use different providers or senders.
No. Knock is an orchestration layer that sits on top of email providers like SendGrid, Amazon SES, and Resend. You connect the provider you already use, and Knock sends each email through it, with workflows, broadcasts, and templates in one place.
Yes. The visual editor builds an email from content blocks. Switch to the code editor to write HTML and CSS, or write MJML. Knock inlines CSS and generates a plain-text version of each email.
A layout wraps your email templates in shared HTML, such as a header, footer, and brand styles, so a change to the layout applies to every template that uses it. You can create more than one layout and pick one per template. The default layout supports dark mode.
Yes. Workflows send transactional email from an API call, such as receipts and password resets. Broadcasts send a one-time email to an audience, such as a product announcement. Both use the same templates, layouts, and providers.
Yes. Turn on link tracking to record clicks and open tracking to record opens for an email channel. Privacy features in some email clients can make open counts less precise. Knock records delivery status from providers that report it, and some providers, such as Amazon SES, need a webhook for delivery tracking.
Yes. Include each attachment as Base64-encoded content in the workflow trigger data, and Knock sends it with the email.
Yes. An email step can override the to, cc, bcc, and reply-to fields, and each field supports Liquid, so you can set it from trigger data or recipient properties. You can also pass provider-specific JSON to customize the request Knock sends to your provider.
Yes. Sandbox mode runs workflows and records each message without sending email through the provider. Because channel settings are per environment, you can also point development at a separate provider or test inbox.
Email messages count toward the same message allowance as every other channel. The Free plan is $0 per month and includes 10,000 messages per month. The Starter plan is $250 per month and includes 50,000 messages, then $0.005/ea. Enterprise plans use volume-based pricing.
A message is one message delivered to one user on one channel. Knock doesn't charge for workflow triggers, for messages that a user's preferences suppress, or for messages that bounce or fail.
Yes. Knock doesn't manage billing for downstream providers. Your email provider bills you for the email it sends, at its own rates.