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There are two ways to send attachments:
  1. From a remote file
  2. From a local file
We currently do not support sending attachments when using our batch endpoint.

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Send attachments from a remote file

Include the path parameter to send attachments from a remote file. This parameter accepts a URL to the file you want to attach. Define the file name that will be attached using the filename parameter. 
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

await resend.emails.send({
  from: 'Acme <[email protected]>',
  to: ['[email protected]'],
  subject: 'Receipt for your payment',
  html: '<p>Thanks for the payment</p>',
  attachments: [
    {
      path: 'https://resend.com/static/sample/invoice.pdf',
      filename: 'invoice.pdf',
    },
  ],
});

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Send attachments from a local file

Include the content parameter to send attachments from a local file. This parameter accepts the Base64 encoded content of the file you want to attach. Define the file name that will be attached using the filename parameter. 
import { Resend } from 'resend';
import fs from 'fs';

const resend = new Resend('re_xxxxxxxxx');

const filepath = `${__dirname}/static/invoice.pdf`;
const attachment = fs.readFileSync(filepath).toString('base64');

await resend.emails.send({
  from: 'Acme <[email protected]>',
  to: ['[email protected]'],
  subject: 'Receipt for your payment',
  text: '<p>Thanks for the payment</p>',
  attachments: [
    {
      content: attachment,
      filename: 'invoice.pdf',
    },
  ],
});

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Embed Images using CID

You can optionally embed an image in the HTML body of the email. Both remote and local attachments are supported. All attachment requirements, options, and limitations apply to embedded inline images as well. Embedding images requires two steps: 1. Add the CID in the email HTML. Use the prefix cid: to reference the ID in the src attribute of an image tag in the HTML body of the email. 
<img src="cid:logo-image" />
2. Reference the CID in the attachment The content id is an arbitrary string set by you, and must be less than 128 characters. 
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

await resend.emails.send({
  from: 'Acme <[email protected]>',
  to: ['[email protected]'],
  subject: 'Thank you for contacting us',
  html: '<p>Here is our <img src="cid:logo-image"/> inline logo</p>',
  attachments: [
    {
      path: 'https://resend.com/static/sample/logo.png',
      filename: 'logo.png',
      contentId: 'logo-image',
    },
  ],
});
Learn more about embedding images.

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View and Download Attachments

You can view and download attachments when viewing a sent email that includes them. To view and download attachments:
  1. Go to Emails.
  2. Navigate to any email you sent with an attachment.
  3. Click on the attachment to download it locally.
Attachments include the filename and an icon to help you identify the type of attachment. We show unique icons for each attachment type:
  • Image
  • PDF
  • Spreadsheet
  • Default (for unknown types)

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Attachment Limitations

  • Emails can be no larger than 40MB (including attachments after Base64 encoding).
  • Not all file types are supported. See the list of unsupported file types.
  • Emails with attachments cannot be scheduled.
  • Emails with attachments cannot be sent using our batching endpoint.

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Examples

Attachments with Next.js (remote file)

See the full source code.

Attachments with Next.js (local file)

See the full source code.