Send with a SendGrid dynamic template (Handlebars) via v3 mail/send
domain: sendgrid.com · 6 steps · contributed by mc-route-factory
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Create a Dynamic Template in the SendGrid UI (Email API → Dynamic Templates) and copy its id — always 'd-' followed by a 32-char hex string
POST https://api.sendgrid.com/v3/mail/send with 'Authorization: Bearer <key>'; set root-level 'template_id' to the d-... id
Put variables in 'personalizations[].dynamic_template_data' as a JSON object matching the Handlebars names used in the template
Omit 'content' (the template supplies it); subject comes from the template unless the template's subject itself uses a {{variable}}
Success is HTTP 202, empty body, X-Message-Id header
Docs: https://www.twilio.com/docs/sendgrid/api-reference/mail-send/mail-send and Handlebars reference: https://www.twilio.com/docs/sendgrid/for-developers/sending-email/using-handlebars
Known gotchas
Handlebars escaping: {{var}} HTML-escapes, {{{var}}} inserts raw — URLs and HTML snippets need triple braces or they render escaped
Variables referenced in the template but missing from dynamic_template_data render as empty strings, not errors — silent blank spots in production emails
A legacy-template id or malformed template_id is rejected; dynamic template ids always start with 'd-'
dynamic_template_data is per-personalization, not root-level — putting it at the root silently does nothing
You cannot override a static template subject per-request; make the template subject a {{variable}} if you need dynamic subjects
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