Thunderbird

How to Forward Email as Attachment in Thunderbird? 2026 Guide

By Admin

Updated: March 23, 2026 ~ 4 Minutes Reading

Table of Contents

It is very easy to forward an email as an attachment in Thunderbird. Mozilla Thunderbird gives you a direct option to attach and send an email using the Forward as Attachment option or drag & drop. You can also do so manually by first exporting the email in popular formats like EML, MSG, etc., and further sending them as attachments to preserve hierarchy.

Here are the exact step-by-step instructions to attach an email in Thunderbird.

When Should You Attach an Email in Thunderbird?

There can be a reason why a user may need to forward an email as an attachment:

  • When sending an email as proof or documentation.
  • Avoid formatting issues while direct forwarding.
  • To forward multiple emails together in a structured way, with threading content intact.

Method 1: Thunderbird Forward as Attachment Option

The best way to attach one Thunderbird email to another email is the Forward as Attachment option. It lets you send multiple emails as an EML file in Thunderbird at once.

  1. Select all the emails you want to attach to another email.
  2. Right-click and then choose Forward & Redirect.
  3. Select the As Attachment option.
    Thunderbird Forward as Attachment Option
  4. Compose the email as usual. 
  5. Enter the recipient address and then press Send. 

Tip: Use Ctrl or Shift to select multiple emails at once.

Method 2: Drag and Drop to Attach an Email in Thunderbird

This method is likely suitable if you have limited email to be forwarded as an attachment in Thunderbird.

  1. Click on New Message to compose an email as usual.
  2. Go to the Mail Window
  3. Select all the emails you want to send as attachments.
  4. Then drag & drop them to the new message composing window.
    Drag and Drop to Attach an Email in Thunderbird
  5. Send the email as usual. 

Method 3: Save and Attach Email in Thunderbird

At times, users may need to forward multiple emails as attachments in Thunderbird or share locally archived emails; the manual save and attach option is the professional way to do so.

Tip:
You can use Thunderbird Converter Tool to bulk export emails in Thunderbird MBOX, EML, MSG or any desired format, all while preserving folder hierarchy, metadata, email header, and exact formatting. A demo version of the tool is available to export 25 email messages per folder for free.

  1. Open Thunderbird and click on New Message
  2. Click on the Attachment icon (Paper Clip on top right) or press Ctrl+Shift+A.
  3. Select the email saved on the desktop
  4. Compose the email as usual and press Send

Troubleshoot Thunderbird Attach Email to Another Email Not Working

In case the drag and drop or forward as attachment option is not working or greyed out in Thunderbird. Try out the following fixes:

  • Check if the attachment size does not exceed the attachment limit set by your email service provider.
  • Make sure you are using the latest version of Mozilla Thunderbird.
  • You can try restraining Thunderbird in safe mode
  • Try clearing out Thunderbird Cache

FAQs: How to Attach an Email in Thunderbird?

Q1: What is the Thunderbird attachment file limit?
Thunderbird is merely an email client and does not set any attachment size limit when sending emails. However, most email service providers do have a set limit of 25 MB.

Q2: Can I forward multiple emails as attachments in Thunderbird?
Yes, using all three methods – Select & Forward As Attachment, drag & drop, and save & attach, you can add multiple emails at once without restrictions.

Q3: What is the difference between Forward email and Forward as attachment in Thunderbird?
When you forward an email in Thunderbird, you send the email content in the body as inline text. But when you add an email as an attachment in Thunderbird, it is sent as an EML file attachment, thus preserving other components of the email.