How to Attach an Email to an Email in Outlook

Attaching an email to another email in Microsoft Outlook is a fundamental skill for professionals who need to maintain clear communication threads, provide evidence for IT support, or share complete conversations without losing original formatting and metadata. Unlike a standard "Forward," which pastes the content of a message into the body of a new one, attaching an email preserves the original message as a separate file (typically .msg or .eml).

The fastest way to attach an email in Outlook is to use the drag-and-drop method: open a new message window, position it next to your inbox, and simply click and drag the desired email into the body of the new message. However, the specific steps can vary significantly depending on whether you are using Classic Outlook, the New Outlook for Windows, Outlook on the Web, or Outlook for Mac.

Why Attach an Email Instead of Forwarding?

Before diving into the "how-to," it is crucial to understand the technical advantages of attaching an email as a file versus using the standard forward function. In our professional testing and daily workflow management, we have identified several key reasons why this method is superior in specific scenarios:

1. Preservation of Metadata and Headers: When you forward an email, the transmission headers (the digital "passport" of the email) are often stripped or modified. Attaching the email keeps these headers intact, which is vital for IT departments investigating phishing attempts or for legal teams performing discovery.
2. Maintaining Formatting: Complex emails with intricate HTML layouts or embedded images can sometimes break when forwarded. Attaching the email ensures the recipient sees exactly what you saw.
3. Organization of Multiple Threads: If you need to send five different related emails to a colleague, forwarding five times creates five separate notifications. Attaching all five to a single email keeps the project organized and professional.
4. Original Attachments: When you forward an email, you might forget to include the original attachments. By attaching the email itself, you are essentially sending a container that includes all original files.

How to Attach an Email in Classic Outlook for Windows

Classic Outlook (the traditional desktop application) remains the most feature-rich version. It offers three distinct ways to attach emails.

The Drag and Drop Method

This is the most intuitive approach and works reliably across nearly all desktop versions of Outlook.

• Step 1: Open Outlook and locate the email you wish to attach in your message list.
• Step 2: Create a new email by clicking New Email in the top left corner.
• Step 3: Resize the new message window so that you can see your inbox behind it.
• Step 4: Click and hold the email from your inbox list.
• Step 5: Drag it into the body of the new message and release.

Pro Tip: If you are replying to an email and want to drag another message into it, the "Reply" pane is often docked within the main window, making dragging difficult. Always click the Pop Out button in the top right corner of the reply area to create a separate window before dragging.

Using the "Attach Item" Ribbon Feature

If you prefer using the menu system, or if your screen real estate is limited, use the built-in "Outlook Item" feature.

• Step 1: In your new message or reply window, navigate to the Insert tab on the ribbon.
• Step 2: Click on Attach Item.
• Step 3: Select Outlook Item from the dropdown menu.
• Step 4: A dialog box titled "Insert Item" will appear. Navigate through your folders (Inbox, Sent Items, etc.) to find the message.
• Step 5: In the "Insert as" section on the right, ensure Attachment is selected (not "Text only").
• Step 6: Click OK.

The "Forward as Attachment" Shortcut

Outlook has a specific command that automates the process of creating a new email with a message already attached.

• Step 1: Select the email in your inbox.
• Step 2: In the Home tab, look for the Respond group.
• Step 3: Click More (often represented by a small arrow next to the Forward button) and select Forward as Attachment.
• Keyboard Shortcut: You can also select the email and press Ctrl + Alt + F to achieve the same result instantly.

How to Attach an Email in the New Outlook and Outlook on the Web

The "New Outlook" (which mirrors the interface of Outlook.com and Office 365 Web) uses a slightly different architecture, often generating .eml files instead of the proprietary .msg format used by the classic version.

The Modern Drag and Drop

In the web-based interface, dragging and dropping is highly efficient but requires the "New Message" to be active.

• Step 1: Click New Mail to start a draft.
• Step 2: In the list of emails in your inbox, click the checkbox or simply grab the message area.
• Step 3: Drag it specifically into the "Attachments" area or the body of the draft.
• Step 4: A box will appear saying "Drop messages here." Once you release the mouse, the email will upload as an .eml attachment.

The "Forward as Attachment" Menu

The New Outlook has simplified its menus, but the feature is still accessible.

• Step 1: Open the email you want to attach.
• Step 2: In the top right of the message header, click the three dots (...) or "More Actions" menu.
• Step 3: Select Other reply actions (if applicable) or look directly for Forward as attachment.
• Step 4: A new composition window will open with the file already attached.

How to Attach an Email in Outlook for Mac

Mac users often face interface differences compared to their Windows counterparts. In our testing on the latest macOS versions, the drag-and-drop method remains the king of convenience.

• Step 1: Open your main Outlook window and the "New Message" window.
• Step 2: Ensure both are visible on your workspace.
• Step 3: Click and drag the message from the list into the new message.
• Step 4: If you are using the "New Outlook for Mac" toggle, the behavior is identical to the web version, resulting in an .eml file.

Technical Deep Dive: MSG vs. EML Formats

When you attach an email in Outlook, the file format created depends on your version and settings. Understanding this is essential for cross-platform compatibility.

In our experience, if you are sending an attachment to someone who does not use Microsoft Outlook (like a client using Gmail), they may struggle to open a .msg file. In these cases, using the New Outlook or the Web version to generate an .eml file is a professional courtesy that ensures the recipient can read the content without specialized software.

Dealing with Outlook Mobile (iOS and Android)

A common frustration among mobile users is the lack of a direct "Attach Email" button in the Outlook app for iOS and Android. As of current versions, you cannot simply drag an email into another on a smartphone.

The Mobile Workaround

If you must send an email as an attachment while on the go, use the "Print to PDF" method:

1. Open the email in the Outlook Mobile app.
2. Tap the three dots (...) in the message header.
3. Select Print (you aren't actually going to print it).
4. In the print preview, use the "Share" icon to Save to Files as a PDF.
5. Create your new email and attach that PDF file.

While this doesn't preserve the .eml metadata, it is the most reliable way to share the exact visual content of an email from a mobile device.

Best Practices for Attaching Emails

To ensure your professional communications remain effective, follow these guidelines gathered from years of corporate workflow analysis:

1. Check the Total Size

Emails attached to other emails can become surprisingly large, especially if the attached message contains its own high-resolution images or documents. Outlook typically has a 20MB to 25MB limit. If you attach five emails that are each 5MB, your message will be blocked.

2. Name Your Attachments (If Saving to Disk)

If you choose to save an email to your desktop before attaching it, rename it to something descriptive. "FW_Update.msg" is less helpful than "Original_Client_Complaint_May_2024.msg."

3. Clear the Context

Never send an attached email without an explanation in the body of the main message. Explain why you are sending the attachment and what specific information the recipient should look for within it.

4. Privacy and Confidentiality

Remember that when you attach an email, you are sending the entire thing—including the signature, previous replies in that thread, and any hidden "BCC" recipients if you were the sender. Always double-check that you aren't accidentally sharing sensitive internal notes that were part of a long thread.

Troubleshooting Common Issues

"The Drag and Drop Isn't Working"

This usually happens for two reasons:

• The Window is Not Popped Out: As mentioned earlier, if you are trying to drag into a docked reply, it often fails. Use the "Pop Out" button.
• Permission Levels: If you are running Outlook "As Administrator" but your file explorer is running at a normal user level, Windows security protocols (UIPI) will block the drag-and-drop action. Ensure both are running at the same permission level.

"Recipient Can't Open the .MSG File"

If your recipient uses a Mac or a web-based client like Gmail, they might see a file called "winmail.dat" or a .msg file they can't open.

• Solution: Re-send the email using Outlook on the Web, which will convert it to the more compatible .eml format.

"The Insert Item Option is Greyed Out"

This typically occurs if you are not currently in the "Compose" mode or if your email format is set to "Plain Text" in a way that restricts certain attachments. Ensure your message is set to HTML format via the Options tab.

Summary: Quick Action Guide

Conclusion

Mastering the ability to attach an email to another email in Outlook is a vital component of modern digital literacy. Whether you use the classic drag-and-drop method or the formal "Insert Item" menu, this technique ensures that your communications are precise, context-rich, and technically sound. By preserving metadata and original formatting, you provide your recipients with the highest quality information possible.

For those working in high-stakes environments like law, IT, or project management, the extra few seconds it takes to attach an email—rather than simply forwarding it—can save hours of confusion and potential data loss.

Frequently Asked Questions (FAQ)

Can I attach multiple emails at once?

Yes. In the desktop versions of Outlook, hold the Ctrl key while clicking different emails in your list to select multiple items. Once highlighted, you can drag the entire group into your new message window simultaneously.

Does attaching an email include its attachments?

Yes. When you attach an email (as an .msg or .eml file), the recipient receives the entire "package." When they open the attached file, they will see any attachments that were originally included in that message.

Why do some attached emails show up as "winmail.dat"?

This is usually a compatibility issue between the Microsoft TNEF format and non-Outlook email clients. To prevent this, ensure your Outlook is set to send messages in HTML or Plain Text format rather than Rich Text, or use the Outlook Web App to send the attachment.

Is there a limit to how many emails I can attach?

The only hard limit is the total file size of your outgoing message (usually 20-25MB). You can attach dozens of small, text-only emails without an issue, but a few emails with large attachments will quickly hit the limit.

Can I attach a "Sent" email to a new message?

Absolutely. Simply navigate to your Sent Items folder and use any of the methods described above (Drag and Drop or Forward as Attachment). The process is identical to attaching a message from your Inbox.