Attachments

There are two ways to send attachments:

From a remote file
From a local file

We currently do not support sending attachments when using our batch endpoint.

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 <onboarding@resend.dev>',
  to: ['delivered@resend.dev'],
  subject: 'Receipt for your payment',
  html: '<p>Thanks for the payment</p>',
  attachments: [
    {
      path: 'https://resend.com/static/sample/invoice.pdf',
      filename: 'invoice.pdf',
    },
  ],
});

$resend = Resend::client('re_xxxxxxxxx');

$resend->emails->send([
  'from' => 'Acme <onboarding@resend.dev>',
  'to' => ['delivered@resend.dev'],
  'subject' => 'Receipt for your payment',
  'html' => '<p>Thanks for the payment</p>',
  'attachments' => [
    [
      'path' => 'https://resend.com/static/sample/invoice.pdf',
      'filename' => 'invoice.pdf'
    ]
  ]
]);

import resend

resend.api_key = "re_xxxxxxxxx"

attachment: resend.RemoteAttachment = {
  "path": "https://resend.com/static/sample/invoice.pdf",
  "filename": "invoice.pdf",
}

params: resend.Emails.SendParams = {
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "subject": "Receipt for your payment",
  "html": "<p>Thanks for the payment</p>",
  "attachments": [attachment],
}

resend.Emails.send(params)

require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "subject": "Receipt for your payment",
  "html": "<p>Thanks for the payment</p>",
  "attachments": [
    {
      "path": "https://resend.com/static/sample/invoice.pdf",
      "filename": 'invoice.pdf',
    }
  ]
}

Resend::Emails.send(params)

import (
	"fmt"

	"github.com/resend/resend-go/v3"
)

func main() {
  ctx := context.TODO()
  client := resend.NewClient("re_xxxxxxxxx")

  attachment := &resend.Attachment{
    Path:  "https://resend.com/static/sample/invoice.pdf",
    Filename: "invoice.pdf",
  }

  params := &resend.SendEmailRequest{
      From:        "Acme <onboarding@resend.dev>",
      To:          []string{"delivered@resend.dev"},
      Subject:     "Receipt for your payment",
      Html:        "<p>Thanks for the payment</p>",
      Attachments: []*resend.Attachment{attachment},
  }

  sent, err := client.Emails.SendWithContext(ctx, params)

  if err != nil {
    panic(err)
  }
  fmt.Println(sent.Id)
}

use resend_rs::types::{CreateAttachment, CreateEmailBaseOptions};
use resend_rs::{Resend, Result};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let from = "Acme <onboarding@resend.dev>";
  let to = ["delivered@resend.dev"];
  let subject = "Receipt for your payment";

  let path = "https://resend.com/static/sample/invoice.pdf";
  let filename = "invoice.pdf";

  let email = CreateEmailBaseOptions::new(from, to, subject)
    .with_html("<p>Thanks for the payment</p>")
    .with_attachment(CreateAttachment::from_path(path).with_filename(filename));

  let _email = resend.emails.send(email).await?;

  Ok(())
}

import com.resend.*;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_xxxxxxxxx");

        Attachment att = Attachment.builder()
                .path("https://resend.com/static/sample/invoice.pdf")
                .fileName("invoice.pdf")
                .build();

        CreateEmailOptions params = CreateEmailOptions.builder()
                .from("Acme <onboarding@resend.dev>")
                .to("delivered@resend.dev")
                .subject("Receipt for your payment")
                .html("<p>Thanks for the payment</p>")
                .attachments(att)
                .build();

        CreateEmailResponse data = resend.emails().send(params);
    }
}

using Resend;
using System.Collections.Generic;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" ); // Or from DI

var message = new EmailMessage()
{
    From = "Acme <onboarding@resend.dev>",
    To = "delivered@resend.dev",
    Subject = "Receipt for your payment",
    HtmlBody = "<p>Thanks for the payment</p>",
};

message.Attachments = new List<EmailAttachment>();
message.Attachments.Add( new EmailAttachment() {
  Filename = "invoice.pdf",
  Path = "https://resend.com/static/sample/invoice.pdf",
} );

var resp = await resend.EmailSendAsync( message );
Console.WriteLine( "Email Id={0}", resp.Content );

curl -X POST 'https://api.resend.com/emails' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d $'{
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "subject": "Receipt for your payment",
  "html": "<p>Thanks for the payment</p>",
  "attachments": [
    {
      "path": "https://resend.com/static/sample/invoice.pdf",
      "filename": "invoice.pdf"
    }
  ]
}'

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 <onboarding@resend.dev>',
  to: ['delivered@resend.dev'],
  subject: 'Receipt for your payment',
  text: '<p>Thanks for the payment</p>',
  attachments: [
    {
      content: attachment,
      filename: 'invoice.pdf',
    },
  ],
});

$resend = Resend::client('re_xxxxxxxxx');

$resend->emails->send([
  'from' => 'Acme <onboarding@resend.dev>',
  'to' => ['delivered@resend.dev'],
  'subject' => 'Receipt for your payment',
  'html' => '<p>Thanks for the payment</p>',
  'attachments' => [
    [
      'filename' => 'invoice.pdf',
      'content' => $invoiceBuffer
    ]
  ]
]);

import os
import resend

resend.api_key = "re_xxxxxxxxx"

f: bytes = open(
  os.path.join(os.path.dirname(__file__), "../static/invoice.pdf"), "rb"
).read()

attachment: resend.Attachment = {"content": list(f), "filename": "invoice.pdf"}

params: resend.Emails.SendParams = {
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "subject": "Receipt for your payment",
  "html": "<p>Thanks for the payment</p>",
  "attachments": [attachment],
}

resend.Emails.send(params)

require "resend"

Resend.api_key = "re_xxxxxxxxx"

file = IO.read("invoice.pdf")

params = {
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "subject": "Receipt for your payment",
  "html": "<p>Thanks for the payment</p>",
  "attachments": [
    {
      "content": file.bytes,
      "filename": 'invoice.pdf',
    }
  ]
}

Resend::Emails.send(params)

import (
	"fmt"
	"os"

	"github.com/resend/resend-go/v3"
)

func main() {
  ctx := context.TODO()
  client := resend.NewClient("re_xxxxxxxxx")

  pwd, _ := os.Getwd()
  f, err := os.ReadFile(pwd + "/static/invoice.pdf")
  if err != nil {
    panic(err)
  }

  attachment := &resend.Attachment{
    Content:  f,
    Filename: "invoice.pdf",
  }

  params := &resend.SendEmailRequest{
      From:        "Acme <onboarding@resend.dev>",
      To:          []string{"delivered@resend.dev"},
      Subject:     "Receipt for your payment",
      Html:        "<p>Thanks for the payment</p>",
      Attachments: []*resend.Attachment{attachment},
  }

  sent, err := client.Emails.SendWithContext(ctx, params)

  if err != nil {
    panic(err)
  }
  fmt.Println(sent.Id)
}

use std::fs::File;
use std::io::Read;

use resend_rs::types::{CreateAttachment, CreateEmailBaseOptions};
use resend_rs::{Resend, Result};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let from = "Acme <onboarding@resend.dev>";
  let to = ["delivered@resend.dev"];
  let subject = "Receipt for your payment";

  let filename = "invoice.pdf";
  let mut f = File::open(filename).unwrap();
  let mut invoice = Vec::new();
  f.read_to_end(&mut invoice).unwrap();

  let email = CreateEmailBaseOptions::new(from, to, subject)
    .with_html("<p>Thanks for the payment</p>")
    .with_attachment(CreateAttachment::from_content(invoice).with_filename(filename));

  let _email = resend.emails.send(email).await?;

  Ok(())
}

import com.resend.*;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_xxxxxxxxx");

        Attachment att = Attachment.builder()
                .fileName("invoice.pdf")
                .content("invoiceBuffer")
                .build();

        CreateEmailOptions params = CreateEmailOptions.builder()
                .from("Acme <onboarding@resend.dev>")
                .to("delivered@resend.dev")
                .subject("Receipt for your payment")
                .html("<p>Thanks for the payment</p>")
                .attachments(att)
                .build();

        CreateEmailOptions params = CreateEmailOptions.builder()
    }
}

using Resend;
using System.Collections.Generic;
using System.IO;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" ); // Or from DI

var message = new EmailMessage()
{
    From = "Acme <onboarding@resend.dev>",
    To = "delivered@resend.dev",
    Subject = "Receipt for your payment",
    HtmlBody = "<p>Thanks for the payment</p>",
};

message.Attachments = new List<EmailAttachment>();
message.Attachments.Add( new EmailAttachment() {
  Filename = "invoice.pdf",
  Content = await File.ReadAllBytesAsync( "invoice.pdf" ),
} );

var resp = await resend.EmailSendAsync( message );
Console.WriteLine( "Email Id={0}", resp.Content );

curl -X POST 'https://api.resend.com/emails' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d $'{
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "subject": "Receipt for your payment",
  "html": "<p>Thanks for the payment</p>",
  "attachments": [
    {
      "content": "UmVzZW5kIGF0dGFjaG1lbnQgZXhhbXBsZS4gTmljZSBqb2Igc2VuZGluZyB0aGUgZW1haWwh%",
      "filename": "invoice.txt"
    }
  ]
}'

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 <onboarding@resend.dev>',
  to: ['delivered@resend.dev'],
  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',
    },
  ],
});

$resend = Resend::client('re_xxxxxxxxx');

$resend->emails->send([
  'from' => 'Acme <onboarding@resend.dev>',
  'to' => ['delivered@resend.dev'],
  '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',
      'content_id' => 'logo-image',
    ]
  ]
]);

import resend

resend.api_key = "re_xxxxxxxxx"

attachment: resend.RemoteAttachment = {
  "path": "https://resend.com/static/sample/logo.png",
  "filename": "logo.png",
  "content_id": "logo-image",
}

params: resend.Emails.SendParams = {
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "subject": "Thank you for contacting us",
  "html": "<p>Here is our <img src=\"cid:logo-image\"/> inline logo</p>",
  "attachments": [attachment],
}

resend.Emails.send(params)

require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "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',
      "content_id": "logo-image",
    }
  ]
}

Resend::Emails.send(params)

import (
	"fmt"

	"github.com/resend/resend-go/v3"
)

func main() {
  ctx := context.TODO()
  client := resend.NewClient("re_xxxxxxxxx")

  attachment := &resend.Attachment{
    Path:  "https://resend.com/static/sample/logo.png",
    Filename: "logo.png",
    ContentId: "logo-image",
  }

  params := &resend.SendEmailRequest{
      From:        "Acme <onboarding@resend.dev>",
      To:          []string{"delivered@resend.dev"},
      Subject:     "Thank you for contacting us",
      Html:        "<p>Here is our <img src=\"cid:logo-image\"/> inline logo</p>",
      Attachments: []*resend.Attachment{attachment},
  }

  sent, err := client.Emails.SendWithContext(ctx, params)

  if err != nil {
    panic(err)
  }
  fmt.Println(sent.Id)
}

use resend_rs::types::{CreateAttachment, CreateEmailBaseOptions};
use resend_rs::{Resend, Result};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let from = "Acme <onboarding@resend.dev>";
  let to = ["delivered@resend.dev"];
  let subject = "Thank you for contacting us";

  let path = "https://resend.com/static/sample/logo.png";
  let filename = "logo.png";
  let content_id = "logo-image";

  let email = CreateEmailBaseOptions::new(from, to, subject)
    .with_html("<p>Here is our <img src=\"cid:logo-image\"/> inline logo</p>")
    .with_attachment(
      CreateAttachment::from_path(path)
        .with_filename(filename)
        .with_content_id(content_id),
    );

  let _email = resend.emails.send(email).await?;

  Ok(())
}

import com.resend.*;

public class Main {
    public static void main(String[] args) {
        Resend resend = new Resend("re_xxxxxxxxx");

        Attachment att = Attachment.builder()
                .path("https://resend.com/static/sample/logo.png")
                .fileName("logo.png")
                .ContentId("logo-image")
                .build();

        CreateEmailOptions params = CreateEmailOptions.builder()
                .from("Acme <onboarding@resend.dev>")
                .to("delivered@resend.dev")
                .subject("Thank you for contacting us")
                .html("<p>Here is our <img src=\"cid:logo-image\"/> inline logo</p>")
                .attachments(att)
                .build();

        CreateEmailResponse data = resend.emails().send(params);
    }
}

using Resend;
using System.Collections.Generic;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" ); // Or from DI

var message = new EmailMessage()
{
    From = "Acme <onboarding@resend.dev>",
    To = "delivered@resend.dev",
    Subject = "Thank you for contacting us",
    HtmlBody = "<p>Here is our <img src=\"cid:logo-image\"/> inline logo</p>",
};

message.Attachments = new List<EmailAttachment>();
message.Attachments.Add( new EmailAttachment() {
  Filename = "logo.png",
  Path = "https://resend.com/static/sample/logo.png",
  ContentId = "logo-image",
} );

var resp = await resend.EmailSendAsync( message );
Console.WriteLine( "Email Id={0}", resp.Content );

curl -X POST 'https://api.resend.com/emails' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d $'{
  "from": "Acme <onboarding@resend.dev>",
  "to": ["delivered@resend.dev"],
  "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",
      "content_id": "logo-image"
    }
  ]
}'

Learn more about embedding images.

View and Download Attachments

You can view and download attachments from sent emails from the dashboard or programmatically through the Attachments API.

From the dashboard

Go to Emails.
Navigate to any email you sent with an attachment.
Click on the attachment to download it locally.

Attachments include the filename and an icon to help you identify the type of attachment. Each attachment type has a unique icon:

Image
PDF
Spreadsheet
Default (for unknown types)

From the API

Use List Attachments to fetch all attachments for a sent email, or Retrieve Attachment to fetch a single one. Both endpoints return a signed download_url that you can use to download the content.

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 sent using our batching endpoint.

Examples

Next.js (TypeScript)

See the full source code.

Next.js (JavaScript)

See the full source code.

PHP

See the full source code.

Laravel

See the full source code.

Python

See the full source code.

Ruby

See the full source code.

Inline Images (CID)

Next.js (TypeScript)

See the full source code.

Next.js (JavaScript)

See the full source code.

PHP

See the full source code.

Laravel

See the full source code.

Python

See the full source code.

Ruby

See the full source code.

​Send attachments from a remote file

​Send attachments from a local file

​Embed Images using CID

​View and Download Attachments

​From the dashboard

​From the API

​Attachment Limitations

​Examples

​Attachments

Next.js (TypeScript)

Next.js (JavaScript)

PHP

Laravel

Python

Ruby

​Inline Images (CID)

Next.js (TypeScript)

Next.js (JavaScript)

PHP

Laravel

Python

Ruby

Send attachments from a remote file

Send attachments from a local file

Embed Images using CID

View and Download Attachments

From the dashboard

From the API

Attachment Limitations

Examples

Attachments

Inline Images (CID)