How to Attach an Email to Another Email (And When Each Method Makes Sense)

Forwarding a message is easy. But attaching an entire email as a file inside another email — preserving its headers, formatting, and metadata — is a different thing entirely. Whether you're building a paper trail, escalating a support case, or sending a thread to someone outside your organization, knowing how to attach email to email correctly saves time and prevents the awkward "I pasted the text below" workaround.

What Does "Attaching an Email to an Email" Actually Mean?

When most people say they want to attach an email, they mean one of two things:

• Forward as attachment — The original email becomes an .eml file attached to a new outgoing message, just like a PDF or image would be.
• Inline forwarding — The email content is pasted into the body of the new message, which looks cleaner but loses original headers and metadata.

These are not the same thing. A forwarded-as-attachment email preserves the original sender address, timestamps, and routing headers. Recipients can open it as a standalone message. An inline forward is essentially quoted text — easier to read at a glance, but easier to alter and lacking forensic integrity.

For legal, compliance, or IT escalation purposes, attaching as an .eml file is almost always the more appropriate choice.

How to Attach an Email as an Attachment in Major Email Clients

Gmail

Gmail doesn't have a dedicated "Forward as Attachment" button in the standard interface, but it supports the feature:

1. Open the email you want to attach.
2. Click the three-dot menu (More options) in the top-right of the message.
3. Select "Forward as attachment."

A new compose window opens with the original email attached as an .eml file. You can add recipients, write a covering note, and send.

Alternatively, in Gmail's list view, you can select multiple emails using checkboxes, then choose More → Forward as attachment to bundle several messages into one outgoing email.

Outlook (Desktop)

Microsoft Outlook has supported this feature for years across its desktop versions:

1. Select the email in your inbox or folder.
2. Go to Home → More → Forward as Attachment, or right-click the message and choose Forward as Attachment.
3. In some versions, you can also drag and drop a message from your folder list directly into the body of an open compose window — it will attach as an .eml or .msg file depending on your Outlook version.

Outlook .msg files are a Microsoft-specific format. Recipients using Outlook can open them natively. Recipients on Mac Mail, Gmail, or mobile clients may need to take extra steps, which is worth considering before you send.

Apple Mail (macOS)

1. Select the message in your inbox.
2. Go to Message → Forward as Attachment from the menu bar.

Apple Mail attaches the message as an .eml file, which is broadly compatible across clients.

Mobile Email Apps 📱

Support varies significantly here. Native iOS Mail allows forwarding as attachment through a long-press gesture on the message. Android's Gmail app supports it through the same three-dot menu as desktop. Many third-party mobile apps — Spark, Airmail, Outlook for iOS/Android — include this feature, but its location differs by app and version.

The .eml File Format: What Recipients Actually Receive

An .eml file is a plain-text file following the MIME standard. It contains:

• Headers — sender, recipient, date, subject, message ID, routing path
• Body — in plain text or HTML, depending on the original message
• Attachments — encoded within the file if the original email had any

Most desktop email clients open .eml files natively. Some users may receive an .eml and not immediately know how to open it — especially on mobile or if they use a webmail interface that doesn't automatically preview the format. This is a real-world friction point, particularly when sending to non-technical recipients.

When Forwarding as Attachment Makes More Sense Than Regular Forwarding

Use forward as attachment when:

• You need to preserve original headers for IT, legal, or compliance review
• You're reporting spam or phishing to your email provider or security team
• You want to attach multiple emails as a bundle to a single message
• The recipient needs the original message structure, not just the text

Use inline forwarding when:

• You want the recipient to read the content easily without opening a file
• You're sharing a quick update in a casual context
• The recipient is on mobile and you want to minimize friction

Variables That Change the Experience

How smoothly this works depends on several factors:

• Your email client — Some clients make forward-as-attachment one click; others bury it or don't support it at all.
• Your recipient's client — An .eml file is widely supported, but .msg files may require Outlook to open properly.
• The original message's complexity — Emails with nested attachments, rich HTML, or embedded images may not render identically when wrapped in an .eml container.
• Organizational IT policy — Some enterprise email environments strip .eml or .msg attachments at the gateway level as a security measure. Your attached email may never arrive.
• Mobile vs. desktop — The feature availability and workflow differs enough between platforms that what takes two clicks on desktop may require navigating menus on mobile.

One Method, Several Outcomes

The underlying concept — wrapping an email as a file inside another email — is straightforward and well-supported. But the experience from composing to delivery to opening on the other end is shaped by which clients are involved on both sides, what the email contains, and what the recipient's environment looks like. 🔍

Those variables don't change the technique, but they do determine whether it works cleanly or requires a fallback plan.