Templates

API base URL: https://api.relayloft.com

A template holds an email's HTML (and optionally its text, subject, from and reply-to) with {{{KEY}}} where values go. Manage them under Templates in the portal, or with Resend's Templates API and a Full access key (resend.templates.*).

Variables

• Write {{{KEY}}} in the HTML, text or subject. Keys are letters, digits and _, up to 50 characters, and each must be declared in variables (key, type string or number, optional fallback_value). Up to 50.
• FIRST_NAME, LAST_NAME, EMAIL, UNSUBSCRIBE_URL, RESEND_UNSUBSCRIBE_URL, contact and this are reserved.
• Values are HTML-escaped in the HTML, so a value can't add markup or links; they go into the text as they are, and into the subject with line breaks removed. They're never put in other headers.
• Substitution only: no conditions, loops or includes, and nothing in a template runs. Anything else in triple braces (such as {{{contact.first_name}}}) is refused when you save.

Drafts and publishing

A new template is a draft. POST /templates/:id/publish makes the current draft the version emails use. Edits after that stay a draft (has_unpublished_versions is true) until you publish again, so sends keep using the published version. Only published templates can be sent. Duplicating makes a new draft named "… (copy)", without the alias.

const { data } = await resend.templates
  .create({
    name: "Order confirmation",
    alias: "order-confirmation",
    from: "Acme <orders@mail.yourcompany.com>",
    subject: "Order {{{ORDER}}}",
    html: "<p>{{{PRODUCT}}} costs {{{PRICE}}}</p>",
    variables: [
      { key: "ORDER", type: "string" },
      { key: "PRODUCT", type: "string", fallbackValue: "Your item" },
      { key: "PRICE", type: "number" },
    ],
  })
  .publish(); // POST /templates, then POST /templates/:id/publish

Also GET /templates (newest first; limit, after, before), GET /templates/:id, PATCH /templates/:id, DELETE /templates/:id and POST /templates/:id/duplicate. Anywhere an id goes, the alias works too. Changes return { "id", "object": "template" }, as Resend's do.

Sending with a template

curl -X POST https://api.relayloft.com/emails \
  -H "Authorization: Bearer $RESEND_API_KEY" -H "Content-Type: application/json" \
  -d '{"to":"user@example.com","template":{"id":"order-confirmation","variables":{"ORDER":"#42","PRICE":499}}}'

• Leave out html and text: sending them with template: { … } is a 422.
• from, subject and reply_to in the send win over the template's; without either, the send needs its own.
• A variable used in the template with no value and no fallback is a 422 that names every missing one. Values are strings up to 2,000 characters or numbers. Values for keys the template doesn't use are ignored.
• Works in batches too. The result goes through every check any email does: verified domain, size, sandbox, limits.

Limits

• 100 templates per app, 256 KB of HTML and 128 KB of text each.
• 500 template changes a day per account (API and portal together).