SendGrid · api · fg-0418

SendGrid recipients see each other's addresses when the to field is an array

Every customer sees the full recipient list in To

Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100

Cause

All addresses in one personalization receive one shared message and can see each other, and an address may appear only once across its to, cc, and bcc. Each request takes at most 1,000 personalizations.

Fix

Put each recipient in its own personalization, or use sendMultiple or isMultiple in the Node SDK, and split lists over 1,000.

Apply

await sgMail.sendMultiple({ to: emails, from, subject, html });  // one personalization per address

Affects: SendGrid v3 Mail Send, @sendgrid/mail 6.x to 8.x, as of 2026-10

Sources

• https://www.twilio.com/docs/sendgrid/for-developers/sending-email/personalizations
• https://www.twilio.com/docs/sendgrid/api-reference/mail-send/errors
• https://github.com/sendgrid/sendgrid-nodejs/blob/main/docs/use-cases/single-email-multiple-recipients.md

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