How to Export Your Raw Email File (.eml) for DKIM Verification

When verifying an email's authenticity, you need the original raw source file — not a forwarded copy. Emails carry a DKIM digital signature that confirms who sent them and that the content hasn't been tampered with. Forwarding an email rewrites its headers and destroys that signature, so we need the untouched original.

Here's how to save it, depending on your email provider.

Why Not Just Forward It?

A standard forward re-renders the message body and rewrites headers, which mathematically invalidates the DKIM signature. The methods below preserve the original bytes exactly as they arrived — a regular forward does not.

Gmail (Web)

1. Open the email in a desktop browser at gmail.com (the mobile app doesn't support this).

2. Click the three vertical dots ⋮ near the top-right of the message.

3. Select Show original — this opens a new tab.

4. Click Download Original at the top of that tab.

Use Download Original, not "Copy to clipboard" — the clipboard option only copies headers.

Apple Mail (macOS)

1. Open the email in Apple Mail on your Mac.

2. Go to File → Save As… from the menu bar.

3. Set the Format to Raw Message Source and save with a .eml extension.

Alternatively, drag the message from your inbox straight onto your desktop — macOS will drop a .eml file automatically. Note that Mail on iPhone or iPad doesn't support this.

Thunderbird

1. Right-click the email in your message list.

2. Choose Save As… and save the file with a .eml extension.

You can also use the menu bar: File → Save As → File (press ≡ first if the menu bar is hidden).

Proton Mail (Web)

1. Open the email at mail.proton.me in a desktop browser.

2. Click the three dots ⋯ at the top of the message.

3. Select View headers, then click Download.

The mobile Proton Mail app doesn't support raw export, so use the web version.

All Other Providers (Outlook, Yahoo, iCloud, etc.)

Most providers — including Outlook on the Web, Yahoo Mail, iCloud Mail, and mobile apps — don't offer a direct raw export option. The workaround below works universally.

1. In your email client, find Forward as Attachment (sometimes labeled "as .eml" or "include original"). Look in the more-actions or overflow menu — it's separate from the regular Forward button.

2. Send it to a Gmail address you control. Leave the subject and body untouched.

3. Open Gmail in a desktop browser and find the message you just sent.

4. Click the attached .eml file — it will open as an embedded message inside Gmail.

5. On that embedded message, click ⋮ → Show original → Download Original.

That downloaded file is your original email with the DKIM signature intact.

Why "Forward as Attachment" and not regular Forward? Forwarding as an attachment wraps the original message in a new envelope without modifying its contents, so the signature survives. A regular forward rewrites everything and breaks it.