Send and receive email on your own domain

Receipts and account email

Receipts, password resets and notices go out as transactional email, with no consent paperwork.

Replies and inbound mail

Customers reply to a receipt or write to a support address, and each message reaches your app over the API as JSON.

Commercial email, with consent

Newsletters and offers go out only with CASL consent on file, each to one recipient, with the unsubscribe link added for you.

Alongside SMS

The same account, API keys, webhook endpoints and prepaid balance as your text messages.

Your domain, verified

DKIM on your domain and a return path on a send subdomain. Nothing in your root domain's existing mail setup changes.

One call or a batch

Send one email to up to 50 recipients across to, cc and bcc, a batch of up to 100 different emails, or one message to up to 500 recipients with their own variables.

Templates with versions

Store templates with declared variables. Edits are drafts until you publish, each publish is a numbered version, and rolling back is one call.

Scheduling

Schedule a send from 1 minute to 30 days ahead, then move or cancel it while it waits. Cancelling refunds the charge.

Attachments

Up to 10 files and 25 MB per email, with the first 2 MB per recipient included. Executable and script files are refused.

Open and click tracking

Turn tracking on or off per domain, and get the first open and first click as webhooks.

Safe retries

Send an Idempotency-Key header and a retried request returns the original email instead of sending, and charging, twice.

curl -X POST https://api.honkio.ca/v1/emails \
  -H "Authorization: Bearer mk_test_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "from": "Acme <onboarding@test.honkio.ca>",
    "to": "delivered@test.honkio.ca",
    "subject": "Your receipt",
    "html": "<p>Thanks for your order.</p>"
  }'

This runs with a test key before you add a domain: the test sender and address need no DNS, and nothing is delivered or charged.

A managed address, ready now

Every account gets an inbound address with nothing to set up, and any name before the @ reaches it.

Or your own domain

Turn on receiving for a domain you already send from and publish one MX record. A subdomain keeps your main mailboxes where they are.

Parsed for you

Each message fires an email.received webhook. Fetch its text, HTML, headers, attachments and SPF, DKIM, DMARC and spam verdicts as JSON, or the raw message.

Safe to display

Ask for sanitized HTML, with scripts and unsafe markup removed and remote images held back.

Reply in the thread

Send your reply with the In-Reply-To and References headers and it lands in the same thread in the customer's mail app.

Caps that protect your balance

Up to 1,000 received messages a day by default. Mail over the cap, mail flagged as a virus and mail your balance cannot pay for is kept as headers only and not charged.

AI agents, on opt-in

The MCP server reads the inbox only when you turn that on, and marks every sender-written field as untrusted content.

Receiving email in the docs

• A commercial email (is_commercial set to true) needs CASL consent on file for its one recipient. Without it the send is refused with HTTP 451 and nothing is charged.
• Commercial email gets an unsubscribe footer and one-click unsubscribe (RFC 8058). An unsubscribe blocks commercial email to that address; receipts and resets still go through.
• Hard bounces and spam complaints add the address to your suppression list, and no email goes to it again unless you remove it.
• If recent live email bounces or draws complaints at a high rate, live email pauses for 24 hours and a webhook says why. SMS and test keys keep working.
• Consent is recorded once per email address, in the same consent records as your SMS.

CASL and suppressions in the docsHow CASL, PIPEDA and Quebec Law 25 apply

• Send from onboarding@test.honkio.ca with a test key and no domain. Nothing is delivered or charged.
• Send to delivered@, bounced@, complained@ or delayed@test.honkio.ca and watch each outcome arrive as a webhook.
• Simulate an inbound email to your test address, with attachments and verdicts, to build the receiving side first.

Email sent

$0.0025 CAD per recipient$2.50 per 1,000 recipients, with 2 MB of attachments included per recipient.

Email received

$0.0025 CAD per messageCovers the first 1 MB of each message, then $0.002 per started MB. Mail blocked as a virus or over your daily cap is free.

A recipient refused for consent, an unsubscribe or a suppression costs nothing, and test mode is always free. The managed inbound address is free; you pay only for the messages it accepts.

Full pricingEmail limits in the docs

Read the privacy policy

SDKs

Official Node.js, Python and PHP clients for sending email and reading received mail.

Laravel mail transport

Add a honkio mailer to config/mail.php and your existing Mailables send through HonkIO.

MCP server

Let Claude, Cursor or VS Code send email through the HonkIO MCP server, and read the inbox if you opt in.

Moving from Resend

Most integrations change the base URL and the key. The migration guide lists the fields that differ, such as the CASL flag and ISO 8601 scheduling.

• Email quickstart
• Sending domains
• Test mode
• Sending and batches
• Templates
• Receiving email
• CASL and suppressions
• Email limits
• Migrating from Resend
• Email webhook events
• SDKs
• MCP server

Do transactional emails need a consent record?

Not in HonkIO. Email is transactional by default and goes out without a consent record. Set is_commercial to true on anything promotional: HonkIO then requires CASL consent on file, adds the unsubscribe footer and honours one-click unsubscribe.

Can I receive email without changing my DNS?

Yes. Every account has a managed inbound address that works with nothing to set up. To receive on your own domain, verify it for sending and publish one MX record, ideally on a subdomain.

How does received email reach my app?

Each accepted message fires an email.received webhook with its metadata. Fetch the full message by id as JSON (text, HTML, headers, attachments and authentication verdicts) or download the raw message. Delivery is at least once, so deduplicate on the email id.

How is email billed?

Per accepted recipient when you send and per accepted message when you receive, from the same prepaid balance as SMS. A recipient refused before sending is not charged, and test mode is free.

Will adding my domain affect the email I already get?

No. Sending uses DKIM on your domain and a return path on a send subdomain, so your root domain's MX records and mailboxes stay as they are. Receiving on your domain is a separate step you turn on.

What happens if my emails start bouncing?

Hard bounces and complaints are suppressed automatically. If more than 5% of your last 200 live emails hard bounce (once you have sent at least 50), or more than 0.1% of your last 1,000 draw complaints, live email pauses for 24 hours and you get an account.sending_paused webhook and an email. SMS keeps sending.

Where is my email stored?

In Canada, in AWS ca-central-1 (Montréal). Content is purged after 90 days, and the attachments and raw message of received mail after 40. API requests are processed on US-hosted infrastructure before they are stored.

I use Resend today. How much has to change?

For most integrations, the base URL and the API key; with the SDK, import Honkio from @honkio/node in place of Resend. The migration guide covers the fields that differ, such as is_commercial for CASL and ISO 8601 scheduling.

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