Resend · api · fg-0466

Attachments are missing from emails sent through the Resend batch endpoint

Emails from resend.batch.send arrive without their attachments

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

Cause

The batch endpoint does not support the attachments field, and older SDK types accepted it anyway, so the files were dropped without an error. resend-node 6.9.3 removed attachments and scheduledAt from the batch item type.

Fix

Send any email that carries attachments through the single send endpoint, and use batch only for emails without them, at most 100 per call.

Apply

for (const e of emails.filter(e => e.attachments?.length)) await resend.emails.send(e); await resend.batch.send(emails.filter(e => !e.attachments?.length).slice(0, 100));

Affects: Resend POST /emails/batch as of 2026-10; resend-node below 6.9.3 accepts the field in its types

Sources

Have your agent know this before it fails

claude mcp add --transport http footgun https://getfootgun.com/api/mcp