How to Attach an Email in Outlook: Forwarding, Embedding, and Sending Messages as Attachments

Attaching one email to another sounds simple, but Outlook gives you several ways to do it — and each method behaves differently depending on your version of Outlook, your recipient's email client, and what you actually need the attached email to do. Understanding the mechanics behind each approach helps you choose the right one for the situation.

What Does "Attaching an Email" Actually Mean?

When most people say they want to attach an email in Outlook, they usually mean one of three things:

• Attaching a file to an email (a document, image, or other file)
• Attaching one email as a file inside another email
• Forwarding an email so its content travels with a new message

These are distinct actions. The first is straightforward. The second and third involve some nuance — particularly around how the recipient receives and opens the content.

How to Attach a File to an Outlook Email

This is the most common task. In Outlook desktop (Windows or Mac):

1. Open a new email or reply window
2. Click Insert in the ribbon
3. Select Attach File
4. Browse your device or recent files and select what you want to send

You can also drag and drop files directly into the compose window. Outlook will display them as attachment chips below the subject line or inline, depending on file type.

In Outlook on the web (previously Outlook Web App or OWA):

1. Click New message or open a reply
2. Click the paperclip icon at the bottom of the compose window
3. Choose to browse your device or attach from OneDrive

📎 One important distinction: attaching from OneDrive sends a link by default, not a copy of the file. The recipient needs access to that OneDrive location to open it. If you want them to have an actual file, select Share as attachment when prompted.

How to Attach an Email Inside Another Email

This is where Outlook has a specific feature many users overlook. You can embed an entire email message as an .msg attachment within a new message. The recipient can open it as a standalone email in their own client.

In Outlook desktop:

1. Open a new compose window
2. Go to Insert → Attach Item → Outlook Item
3. A dialog will appear showing your folder structure — navigate to the email you want to attach
4. Select it and click OK

Alternatively, you can drag an email from your inbox directly into the body of a new compose window. Outlook will attach it as a .msg file automatically. This is often the fastest method.

What the recipient sees: A .msg file attachment. When they double-click it, it opens as a full email — with headers, sender info, and original formatting intact. This is particularly useful when forwarding evidence of a conversation or escalating a thread to someone outside the original exchange.

Forwarding vs. Attaching: Key Differences

Forwarding is faster and works well for casual sharing. Attaching as a .msg preserves the full message metadata — timestamps, original sender addresses, and reply chains — which matters when the authenticity of the communication is important.

Attaching Multiple Emails at Once

If you need to send several emails as attachments in one message, the drag-and-drop method scales well in Outlook desktop. Select multiple messages in your inbox using Ctrl+Click (Windows) or Cmd+Click (Mac), then drag them all into an open compose window. Each message attaches as a separate .msg file.

This isn't currently as smooth in Outlook on the web, where the Attach Item function for embedding emails isn't available. Web users typically need the desktop app for this workflow.

Attaching Emails on Mobile (Outlook for iOS and Android)

The Outlook mobile app doesn't support attaching emails as .msg files. Your options on mobile are limited to:

• Forwarding the email to the recipient directly
• Sharing the email via your device's share sheet (availability depends on what other apps are installed)

If your workflow requires attaching emails as files regularly, the desktop client or web version is better suited to the task.

Variables That Affect How This Works in Practice

Several factors shape the experience:

• Outlook version: Classic Outlook desktop, the newer "New Outlook" for Windows, Outlook for Mac, and Outlook on the web have slightly different UIs and feature availability
• Recipient's email client: .msg files open natively in Outlook but may require workarounds in Gmail, Apple Mail, or other clients
• File size limits: Most email servers cap total message size somewhere between 10MB and 25MB — attaching large emails or emails with embedded images can push you over that threshold
• OneDrive integration: If your organization uses Microsoft 365, attachment behavior may be modified by admin policies that default to link-sharing instead of file copies
• Exchange or IMAP setup: Some features, like the Attach Item dialog, rely on your mailbox being configured through Exchange or Microsoft 365 — IMAP-connected accounts may behave differently

🔍 The "right" method also depends on why you're attaching the email in the first place. Sharing a receipt, escalating a complaint, archiving a thread, or meeting a compliance requirement each puts different weight on metadata preservation, file format compatibility, and how the recipient is set up to receive it.

Whether the .msg format, a forwarded message, or a cloud-shared link best fits your workflow depends on the specifics of your setup — and what the person on the other end is actually expecting to receive.