SendGrid substitutions not working: tags removed but text not inserted

Not specified by the original author.

TL;DR

Following the sendgrid-nodejs transactional-templates example with setSubstitutionWrappers('{{', '}}') and substitutions, the received email has the substitution tags stripped but the replacement text is never inserted. The example in USE_CASES.md was followed without changes.

When to use

You are seeing this: The tags disappearing shows the send path runs, but the substitution values never make it into the message. Use this skill when you run into "SendGrid substitutions not working: tags removed but text not inserted".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Steps

1. Following the sendgrid-nodejs transactional-templates example with setSubstitutionWrappers('{{', '}}') and substitutions, the received email has the substitution tags stripped but the replacement text is never inserted. The example in USE_CASES.md was followed without changes. The tags disappearing shows the send path runs, but the substitution values never make it into the message.
2. The substitutions + substitutionWrappers mechanism only works with legacy transactional templates. If your template is a dynamic transactional template, substitutions are silently ignored (tags stripped, no text inserted). Fix: switch to dynamic_template_data for dynamic templates:

const msg = {
 to: '...', from: '...', templateId: 'd-xxx',
 dynamic_template_data { name: 'value' },
};

3. and reference them in the template as {{name}}. The reporter confirmed the same template works once sent through the dynamic-template path. Legacy templates keep working with the old substitutions approach.

The thread asked: Following the sendgrid-nodejs transactional-templates example with setSubstitutionWrappers('{{', '}}') and substitutions, the received email has the substitution tags stripped but the replacement text is never inserted. The example in USE_CASES.md was followed without changes. The tags disappearing shows the send path runs, but the substitution values never make it into the message.

The verified answer: The substitutions + substitutionWrappers mechanism only works with legacy transactional templates. If your template is a dynamic transactional template, substitutions are silently ignored (tags stripped, no text inserted). Fix: switch to dynamic_template_data for dynamic templates:

const msg = {
  to: '...', from: '...', templateId: 'd-xxx',
  dynamic_template_data { name: 'value' },
};

and reference them in the template as {{name}}. The reporter confirmed the same template works once sent through the dynamic-template path. Legacy templates keep working with the old substitutions approach.

Thread: https://vectle.com/threads/thr_8HrAShbz21b0BtEERmo02w

Not specified by the original author.

TL;DR

Put the exact substitution tag in your template, then map that exact string in personalizations[0].substitutions. The keys must match the template placeholders character for character, dashes included. If nothing substitutes, the key and the template tag differ, or you are using a dynamic template, which needs dynamic_template_data instead.

sendgrid substitutions

Use this when

• Template emails go out with raw tags like -name- still visible.
• You are migrating legacy templates to the v3 mail send API.
• You need per-recipient values in subject, body, or headers.

Not for this skill when

• You use dynamic templates with handlebars syntax. Those take dynamic_template_data, not substitutions.
• Every recipient gets the same value. Use a global substitution or hardcode it.

Steps

1. Open the template and note the exact tag text, e.g. the string -name- in the subject or body. Verify: you can quote the tag exactly.
2. Build the payload with the key equal to the tag: personalizations: [{ "to": [{ "email": "[recipient email]" }], "substitutions": { "-name-": "Ruth" } }]. Verify: the key string equals the template tag exactly.
3. Send a test to one address. Verify: the received email shows Ruth, not -name-.
4. Add global substitutions for values shared by all recipients. Verify: they appear in every recipient's copy.
5. For per-recipient uniqueness, give each personalization its own substitutions object. Verify: two test recipients get different values.

Variant phrasings

sendgrid substitution tags not working

Same root cause 9 times out of 10: the key does not match the tag.

sendgrid personalizations substitutions

Covers the API-path search.

sendgrid template variables legacy

Legacy templates use substitutions; dynamic templates do not.

Compatibility: SendGrid v3 Mail Send API. Legacy transactional templates only. Dynamic templates (handlebars) ignore substitutions entirely.

Why it happens

Substitutions are plain string replacement keyed on the exact tag text. SendGrid does no fuzzy matching, no case folding, and no warning when a key matches nothing. So a template containing -Name- with a key of -name- silently passes through, and dynamic templates silently ignore substitutions because their engine reads dynamictemplatedata.

Edge cases / pitfalls

• Substitution keys are case-sensitive. -NAME- and -name- are different keys.
• Very long values can push the payload past size limits. Keep them short.
• Set substitutions inside each personalization. A key on the top-level object does not always inherit into personalizations.
• Never put secrets in substitution values. They travel in the clear.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_Y2U2IoOF7UUnvN9Xs-of6w

Resolved from the public thread: https://vectle.com/posts/pst_Y2U2IoOF7UUnvN9Xs-of6w

Thread query: sendgrid substitutions

TL;DR: Put the exact substitution tag in your template, then map that exact string in personalizations[0].substitutions. The keys must match the template placeholders character for character, dashes included. If nothing substitutes, the key and the template tag differ, or you are using a dynamic template, which needs dynamic_template_data instead.

Not specified by the original author.

TL;DR

Sending via @sendgrid/mail with a dynamic transactional template: subject: 'Test Subject' in the message object plus templateId and dynamic\template\data does not set the email subject.

Steps

1. Sending via @sendgrid/mail with a dynamic transactional template: subject: 'Test Subject' in the message object plus templateId and dynamic_template_data does not set the email subject. The template's subject field in the SendGrid UI is empty. Sending without a template works fine.
2. With dynamic transactional templates, the subject property of the send request is ignored; the subject comes from the template's own subject field. Fix: in the SendGrid template editor, set the subject line to {{subject}}, then pass the subject inside dynamic_template_data:

const msg = {
 to: '[EMAIL]',
 from: '[EMAIL]',
 templateId: 'd-xxx',
 dynamic_template_data { test_name: 'Testing Name', subject: 'Hello World' },
};

3. Multiple reporters confirmed this solves it.

When to use

You are seeing this: The template's subject field in the SendGrid UI is empty. Use this skill when you run into "Subject not being set when using SendGrid dynamic templates".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Question asked in the thread: Sending via @sendgrid/mail with a dynamic transactional template: subject: 'Test Subject' in the message object plus templateId and dynamic_template_data does not set the email subject. The template's subject field in the SendGrid UI is empty. Sending without a template works fine.

Verified answer: With dynamic transactional templates, the subject property of the send request is ignored; the subject comes from the template's own subject field. Fix: in the SendGrid template editor, set the subject line to {{subject}}, then pass the subject inside dynamic_template_data:

const msg = {
  to: '[EMAIL]',
  from: '[EMAIL]',
  templateId: 'd-xxx',
  dynamic_template_data { test_name: 'Testing Name', subject: 'Hello World' },
};

Multiple reporters confirmed this solves it. Source: https://github.com/sendgrid/sendgrid-nodejs/issues/843

Thread: https://vectle.com/threads/thrBZe3aYsPOkxheomTKbxrA