When you forward an email, formatting can get messy, and metadata, such as timestamps and subject lines, are sometimes stripped out. If you’re forwarding a business email as a verifiable record or want the recipient to see exactly what you received, attaching the email keeps the original message fully intact.

Most email services attach emails as .eml files, which preserve original formatting and attachments. You can attach an email to an email in Gmail, Outlook, and Proton Mail. 

How to attach an email to an email in Gmail

Forward an email as an attachment 

  1. Select the checkbox next to the emails you want to forward as an attachment.
  2. Select More (or the three vertical dots) and select Forward as attachment.
  3. Add your recipients, compose your message, and click Send.

You can forward as many emails as attachments as you want, but if the total exceeds 25 MB, Gmail will attach them via a Google Drive link.

Find out more about Gmail’s attachment size limits and how to send large files via email.

Download and attach an email 

  1. Open the email you want to send as an attachment.
  2. Click the three vertical dots in the email and select:
  • Download message: To save the email as an .eml file.
  • Print: To save the email as a .pdf file.
  1. In your new email, select Attach files (the paperclip icon) to attach the downloaded email. You can also drag and drop a previously downloaded email directly into the message body.
  2. Add your recipients, compose your message, and click Send.

Note: To ensure the email appears as the original when saving as .pdf, check that Headers and footers and Background graphics are selected. You can do this by selecting More settings from the pop-up.

How to attach an email to an email in Outlook

There are two versions of Outlook: New Outlook and Classic Outlook. The steps are broadly similar, with differences marked below. 

Forward an email as an attachment 

  1. Open the email you want to forward as an attachment.
  2. Select More actions (the three horizontal dots) → Other reply actions → Forward as attachment.
  3. A new email window opens with the email attached as an .eml or .msg file, depending on your Outlook version.
  4. Add your recipients, compose your message, and click Send.

Download and attach an email 

  1. Open the email you want to send as an attachment.
  2. Select More (the three horizontal dots) and select:
    • Download: To save the email as an .eml (or .msg if using classic Outlook).
    • Print: To save the email as a .pdf file.
  3. In your new email, select Attach a file to this item (the paperclip icon) to attach the downloaded email. You can also drag and drop a previously downloaded email directly into the message body.
  4. Add your recipients, compose your message, and click Send.

How to attach an email to an email in Proton Mail

To attach an email in Proton Mail, you must download and upload the email to your draft. 

Download and attach an email  

  1. Open the email you want to send as an attachment.
  2. Select More (the three horizontal dots) and select:
    • Export: To save the email as an .eml file.
    • Print: To save the email as a .pdf file.
  3. In your new email, select Attachments (the paperclip icon) to attach the downloaded email. You can also drag and drop a previously downloaded email directly into the message body.
  4. Add your recipients, compose your message, and click Send.

Proton’s privacy-first design means all your emails are end-to-end encrypted by default, so that they remain secure and private. When you export an email from Proton Mail, the exported file is decrypted locally on your device so it can be viewed in other email clients or applications. 

Attaching emails works better than forwarding 

Attaching an email instead of forwarding it helps preserve the original message, including formatting, timestamps, attachments, and sender details. Whether you use Gmail, Outlook, or Proton Mail, attaching emails can make conversations clearer and provide a more reliable record of what was originally sent.

If you regularly share sensitive business emails or documents, using a privacy-first email service like Proton Mail helps keep your communications secure with end-to-end encryption by default.