Bug Report

The mapAttachments function in @payloadcms/email-resend has two bugs that make all email attachments arrive corrupt or fail entirely.

Bug 1: path is not supported

The docs recommend using path for cloud storage:

attachments: [{ filename: 'invoice.pdf', path: mediaDoc.url }]

But mapAttachments requires content to exist and throws if it's missing:

if (!attachment.filename || !attachment.content) {
  throw new APIError('Attachment is missing filename or content', 400);
}

The path property is defined in the Attachment type but never read or forwarded.

Bug 2: content as base64 string produces corrupt files

The docs also show passing base64 content:

attachments: [{ filename: 'invoice.pdf', content: fileBuffer.toString('base64') }]

But mapAttachments wraps the string in Buffer.from(attachment.content) (treating base64 as UTF-8 text). This Buffer is then serialized via JSON.stringify(), producing {"type":"Buffer","data":[83,71,...]} instead of the base64 string that the Resend REST API expects. The attachment arrives corrupt.

Suggested fix

mapAttachments should:

1. Pass path through when content is absent
2. Keep base64 strings as-is (don't wrap in Buffer) since JSON.stringify is used downstream

Reproduction

Any call to payload.sendEmail() with attachments using the Resend adapter.

Version: @payloadcms/email-resend@3.73.0 (also present on main branch as of March 2026)