🐞 Issue: UTF-8 encoding failure in `From.name` and email headers (Node.js SendGrid SDK)

[leonkwan46]

Summary

When using @sendgrid/mail in a Node.js (Firebase Functions) environment, UTF-8 characters in email headers such as From.name and Subject are not consistently preserved across email clients, especially iOS Mail.

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Expected behavior

UTF-8 characters (e.g. è) in sender name and subject should be correctly encoded and displayed across all email clients.

Example:
From: Tonalè no-reply@domain.com
Subject: Tonalè Verification

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Actual behavior

• UTF-8 characters in From.name are displayed incorrectly (e.g. ? on iOS Mail)
• Gmail may render correctly, but iOS Mail consistently fails
• Subject and From headers appear to be encoded or downgraded incorrectly in transit
• Branding characters (e.g. accented letters) are lost in headers

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Technical setup

• Node.js (Firebase Cloud Functions)
• @sendgrid/mail SDK
• Transactional emails (verification, password reset, email change)

Example:
from: { name: "Tonalè", email: "no-reply@domain.com" }

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What was tested (no success)

• Raw UTF-8 strings in from.name
• RFC 2047 encoding (=UTF-8 base64 style encoding)
• Base64 encoding via Node.js Buffer
• Latin-1 / ISO-8859-1 pre-encoding
• HTML body encoding (works correctly — only headers are affected)

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Key observation

SendGrid appears to:

• Normalize or re-encode MIME headers internally
• Potentially downgrade encoding to non-UTF-8 (7-bit / ISO-8859-1)
• Result in corrupted display of non-ASCII characters in strict email clients (notably iOS Mail)

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Impact

• Inconsistent branding in email sender name
• Broken display of accented characters in Apple Mail / iOS Mail
• Cannot reliably use non-ASCII characters in email headers

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Request

Could you confirm:

• Whether UTF-8 is fully supported in From.name and Subject via the Node.js SDK
• Whether SendGrid performs internal header normalization or re-encoding
• Recommended best practice for ensuring consistent rendering across all major email clients (especially iOS Mail)